diff --git a/src/api/BaseApi.ts b/src/api/BaseApi.ts
index 04ade2a..664343e 100644
--- a/src/api/BaseApi.ts
+++ b/src/api/BaseApi.ts
@@ -240,6 +240,20 @@ class Base extends Abstract {
         return this.postRequest({ url, params: { logoText } });
     }
 
+    // ===== 默认壁纸（平台/学校两级，壁纸三级默认轮 2026-10-09；后端契约见 SchSettingsController#schWallpaper）=====
+
+    /** 读默认壁纸（已登录可读）：{wallpaperUrl: string|null, schId=实际命中层}——本校空 → 平台层 → null */
+    getSchWallpaper() {
+        const url = path + "/schWallpaper";
+        return this.getRequest<{ wallpaperUrl: string | null; schId: number }>({ url });
+    }
+
+    /** 保存默认壁纸（仅学校管理员/超管）：URL 取管理池返回的绝对地址原样存，≤255；空串=清空本级 */
+    saveSchWallpaper(wallpaperUrl: string) {
+        const url = path + "/saveSchWallpaper";
+        return this.postRequest({ url, params: { wallpaperUrl } });
+    }
+
     // ===== 学校默认头像样式（默认头像轮 2026-09-30；后端契约见 SchSettingsController#schAvatarStyle）=====
 
     /**
diff --git a/src/assets/styles/header.scss b/src/assets/styles/header.scss
index 7c2663c..6c3f644 100644
--- a/src/assets/styles/header.scss
+++ b/src/assets/styles/header.scss
@@ -24,16 +24,23 @@
         box-shadow: 0px 4px 10px 0px rgba(0, 0, 0, 0.08);
     }
 
+    & .logo-wrap {
+        display: flex;
+        align-items: center;
+        flex-shrink: 0;
+    }
+
     & .logo-box {
         height: 36px;
     }
 
     & .logo-text {
         margin-left: 10px;
-        font-size: 16px;
-        font-weight: 600;
+        font-size: 22px;
+        font-weight: 700;
         color: #252b35;
         white-space: nowrap;
+        letter-spacing: 0.5px;
     }
 
     & .operate-container {
diff --git a/src/components/Header.vue b/src/components/Header.vue
index 2f81a56..763158f 100644
--- a/src/components/Header.vue
+++ b/src/components/Header.vue
@@ -1,7 +1,9 @@
 <template>
     <header :class="headerClass">
-        <img v-if="!!logoUrl" :src="baseUrl + '/image/default-logo.png'" v-real-img="logoUrl" class="logo-box" alt="" />
-        <span v-if="logoText" class="logo-text">{{ logoText }}</span>
+        <div class="logo-wrap">
+            <img v-if="!!logoUrl" :src="baseUrl + '/image/default-logo.png'" v-real-img="logoUrl" class="logo-box" alt="" />
+            <span v-if="logoText" class="logo-text">{{ logoText }}</span>
+        </div>
         <ul class="operate-container fix">
             <li v-if="isWidgetIconShow" :class="{ active: isWidgetShow }">
                 <div class="icon-box" v-wave @click="toggleWidgetShow">
diff --git a/src/views/Settings.vue b/src/views/Settings.vue
index fe11789..39c2f68 100644
--- a/src/views/Settings.vue
+++ b/src/views/Settings.vue
@@ -351,20 +351,22 @@
                 <template v-else>
                     <div class="pane-head">
                         <h3>壁纸<span class="scope">{{ curLayer === 'platform' ? '系统壁纸池' : '校区壁纸池' }}</span></h3>
-                        <p>维护{{ curLayer === 'platform' ? '平台内置（schId=0）系统壁纸' : '本校可选壁纸' }}池：上传、删除，供师生在「壁纸」中选用。
-                            壁纸是每个用户的自选项，本层只提供可选项，不代替用户指定。</p>
+                        <p>维护{{ curLayer === 'platform' ? '平台内置（schId=0）系统壁纸' : '本校可选壁纸' }}池：上传、删除，供师生在「壁纸」中选用；
+                            并可从池中选定<b>本级默认壁纸</b>——成员未自选壁纸时按「本校默认 → 平台默认」回落生效。</p>
                     </div>
                     <div class="sec-card">
-                        <h4>{{ curLayer === 'platform' ? '平台系统壁纸' : '本校校区壁纸' }} <span class="tag">本级可维护</span></h4>
+                        <h4>{{ curLayer === 'platform' ? '平台系统壁纸' : '本校校区壁纸' }} <span class="tag">本级可维护 · 点选为默认</span></h4>
                         <div class="wall-grid">
                             <div v-if="layerWallPool.length === 0" class="logo-empty">暂无壁纸，请先上传</div>
                             <div
                                 v-for="w in layerWallPool"
                                 :key="w.id"
-                                class="wall-item"
+                                :class="['wall-item', { sel: wallSelUrl === w.url }]"
                                 :style="{ background: 'center / cover no-repeat url(' + w.url + ')' }"
+                                @click="wallSelUrl = w.url"
                             >
                                 <i class="del" title="删除" @click.stop="onDeleteWallpaper(w)">×</i>
+                                <i class="tick">✓</i>
                             </div>
                         </div>
                         <div class="form-row form-row--last form-row--top">
@@ -378,18 +380,26 @@
                             </div>
                         </div>
                     </div>
-                    <!-- 上级只读参考池：校管视角下的平台系统壁纸（type=0，可选用不可删）；超管视角为空 -->
+                    <!-- 上级只读参考池：校管视角下的平台系统壁纸（type=0，可选用为本级默认不可删）；超管视角为空 -->
                     <div v-if="upperWallPool.length > 0" class="sec-card">
-                        <h4>平台系统壁纸 <span class="tag">只读参考</span></h4>
+                        <h4>平台系统壁纸 <span class="tag">只读参考 · 可选用为本级默认</span></h4>
                         <div class="wall-grid">
                             <div
                                 v-for="w in upperWallPool"
                                 :key="w.id"
-                                class="wall-item"
+                                :class="['wall-item', { sel: wallSelUrl === w.url }]"
                                 :style="{ background: 'center / cover no-repeat url(' + w.url + ')' }"
-                            ></div>
+                                @click="wallSelUrl = w.url"
+                            >
+                                <i class="tick">✓</i>
+                            </div>
                         </div>
                     </div>
+                    <div class="pane-foot">
+                        <button class="btn primary" :disabled="wallDefaultSaving || !wallSelUrl" @click="onSaveWallDefault">设为本级默认</button>
+                        <button class="btn plain" :disabled="wallDefaultSaving || !layerWallConfigured" @click="onClearWallDefault">清空本级默认</button>
+                        <span class="hint">{{ wallDefaultHitLabel }}</span>
+                    </div>
                 </template>
             </div>
 
@@ -1076,6 +1086,60 @@ async function onClearLogoText() {
     }
 }
 
+/* ===== 默认壁纸（平台/学校两级，壁纸三级默认轮 2026-10-09）：管理员从本级池点选，
+ *  成员未自选壁纸时后端按「本校默认 → 平台默认 → 池内最新」兜底（getUserSettings 生效链）===== */
+const wallSelUrl = ref("");
+const layerWallHitSchId = ref<number | null>(null);
+const wallDefaultHasValue = ref(false);
+const wallDefaultSaving = ref(false);
+/** 本级是否真配置过（对齐主题/LOGO 文字层口径：平台层一律按本级，校级看命中层） */
+const layerWallConfigured = computed(() => wallDefaultHasValue.value && (curLayer.value === "platform" || layerWallHitSchId.value !== 0));
+const wallDefaultHitLabel = computed(() => {
+    if (curLayer.value === "platform") {
+        return wallDefaultHasValue.value ? "平台默认已配置" : "平台默认未配置（成员未自选时回落壁纸池最新一张）";
+    }
+    return layerWallConfigured.value ? "本校已配置" : "未配置本级，当前生效：平台默认";
+});
+
+async function loadWallDefault() {
+    try {
+        const res = await BaseApi.getSchWallpaper();
+        layerWallHitSchId.value = res?.schId ?? null;
+        wallDefaultHasValue.value = !!res?.wallpaperUrl;
+        wallSelUrl.value = res?.wallpaperUrl || "";
+    } catch (e) {
+        /* 读取失败不打扰 */
+    }
+}
+
+/** 保存/清空走同一端点（saveSchWallpaper）：空串＝清空本级（后端存 null）；成功后回读一次刷新命中态 */
+async function onSaveWallDefault() {
+    if (wallDefaultSaving.value) return;
+    wallDefaultSaving.value = true;
+    try {
+        await BaseApi.saveSchWallpaper(wallSelUrl.value.trim());
+        Message.success("默认壁纸已保存，成员未自选壁纸时生效");
+        await loadWallDefault();
+    } catch (error) {
+        Message.error("保存失败:" + error);
+    } finally {
+        wallDefaultSaving.value = false;
+    }
+}
+async function onClearWallDefault() {
+    if (wallDefaultSaving.value) return;
+    wallDefaultSaving.value = true;
+    try {
+        await BaseApi.saveSchWallpaper("");
+        Message.success("已清空本级默认壁纸");
+        await loadWallDefault();
+    } catch (error) {
+        Message.error("操作失败:" + error);
+    } finally {
+        wallDefaultSaving.value = false;
+    }
+}
+
 /* ===== wallpaper pane · my 层（个人壁纸，2026-10-02 任务A；S4 三层化后仅 curLayer==='my' 渲染）=====
  * 能力复制自 Header「设置壁纸」模态框（模态框保留不动）：列表 getUserWallpaperList（type 0=系统/1=校区/2=个人）、
  * 点选即保存 checkWallpaper（与模态框 onClickWallpaper 同语义）、上传走 /api/wallpaperUpload（普通用户落 type=2 个人壁纸）、
@@ -1138,6 +1202,7 @@ watch(curPane, pane => {
     if (pane === "wallpaper") {
         if (isAdmin.value) {
             if (wallpaperManageList.value.length === 0) loadManageLists();
+            loadWallDefault();
         } else {
             loadMyWallpaperList();
         }