diff --git a/README.md b/README.md
index 9ff6cca..0058ce9 100644
--- a/README.md
+++ b/README.md
@@ -36,6 +36,7 @@ pmm install --gitea https://git.example.com/owner/repo   # Gitea/Forgejo（含
 pmm install --git owner/repo --host forgejo               # 强制指定主机类型
 
 pmm mirror list / add <名> <源> / use <名> / remove <名>
+pmm self-update                  # 从镜像安装最新版 pmm+pdm（自动识别本机 os/arch）
 pmm list
 pmm help / version
 pmm install <pkg> -pd          # 安装到 D:\.pmm（可换成 -pc 回到 C 盘，-px 任意盘）
diff --git a/src/install.c b/src/install.c
index 5edaba8..4118ca1 100644
--- a/src/install.c
+++ b/src/install.c
@@ -303,6 +303,11 @@ static const char *cur_os_name(void) {
     switch (pmm_detect_os()) { case OS_WINDOWS: return "windows"; case OS_LINUX: return "linux";
                                case OS_MACOS: return "macos"; default: return "any"; }
 }
+static const char *cur_arch_name(void) {
+    const char *av = getenv("PMM_ARCH_OVERRIDE"); /* debug/testing */
+    if (av && *av) return av;
+    return pmm_detect_arch();
+}
 
 int install_from_registry(const char *name, const char *spec, const char *mirror_active) {
     if (!name || !*name) return -1;
@@ -364,18 +369,21 @@ int install_from_registry(const char *name, const char *spec, const char *mirror
     }
 
     const char *osn = cur_os_name();
+    const char *arch = cur_arch_name();
     JsonValue *variants = json_get(meta, "variants");
     const char *dl = NULL, *file = NULL;
     char *want_sha = NULL;
     const char *chosen = NULL;
     if (variants && variants->count > 0) {
-        /* pick highest variant that matches OS (or 'any') + version spec */
+        /* pick highest variant matching OS + ARCH (or 'any') + version spec */
         const char *bestver = NULL;
         for (int i = 0; i < variants->count; i++) {
             JsonValue *v = json_at(variants, i);
             if (!v || v->type != JSON_OBJECT) continue;
             const char *vos = json_str(v, "os"); if (!vos) continue;
             if (strcmp(vos, osn) != 0 && strcmp(vos, "any") != 0) continue;
+            const char *varch = json_str(v, "arch");
+            if (varch && varch[0] && strcmp(varch, arch) != 0 && strcmp(varch, "any") != 0) continue;
             const char *ver = json_str(v, "version"); if (!ver) continue;
             if (spec && *spec && !spec_match(ver, spec)) continue;
             if (!bestver || vcmp(ver, bestver) > 0) { bestver = ver; chosen = ver;
@@ -383,11 +391,11 @@ int install_from_registry(const char *name, const char *spec, const char *mirror
                 const char *s = json_str(v, "sha256"); free(want_sha); want_sha = s ? strdup(s) : NULL; }
         }
         if (!chosen) {
-            fprintf(stderr, "pmm: no version of '%s' for os=%s%s%s\n", name, osn,
+            fprintf(stderr, "pmm: no version of '%s' for os=%s arch=%s%s%s\n", name, osn, arch,
                     (spec && *spec) ? " satisfying '" : "", (spec && *spec) ? spec : "");
             json_free(meta); mirrors_free(ml); return -1;
         }
-        printf("pmm: selected %s@%s (os=%s)\n", name, chosen, osn);
+        printf("pmm: selected %s@%s (os=%s arch=%s)\n", name, chosen, osn, arch);
     } else {
         /* legacy single-platform entry */
         dl = json_str(meta, "url"); file = json_str(meta, "file");
diff --git a/src/main.c b/src/main.c
index 2ccb5ea..c5cef0d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -356,6 +356,21 @@ int main(int argc, char **argv) {
         if (argc < 3) { fprintf(stderr, "pmm: usage: pmm remove <pkg>\n"); return 1; }
         return pdm_remove(argv[2]) == 0 ? 0 : 1;
     }
+    /* pmm self-update: install the latest 'pmm' tool package (auto os+arch) */
+    if (strcmp(argv[1], "self-update") == 0 || strcmp(argv[1], "update") == 0) {
+        PmmConfig cfg; MirrorSel mirror;
+        load_config(&cfg);
+        load_mirror(&cfg, &mirror);
+        printf("pmm: self-update -> installing latest pmm (%s/%s)\n",
+               pmm_os_name(pmm_detect_os()), pmm_detect_arch());
+        int rc = install_from_registry("pmm", NULL, mirror.name);
+        free(cfg.registry_url); free(cfg.mirror_name);
+        free(mirror.name); free(mirror.api_base);
+        if (rc == 0)
+            printf("pmm: updated. New tools are under %s/bin (pmm/pdm). Re-run from there, or add it to PATH.\n",
+                   pmm_config_dir((char[1024]){0}, 1024));
+        return rc == 0 ? 0 : 1;
+    }
 
     if (strcmp(argv[1], "install") == 0) {
         if (argc >= 3 && (strcmp(argv[2], "--git") == 0 || strcmp(argv[2], "--github") == 0 ||
diff --git a/src/pmm.c b/src/pmm.c
index b999e6d..04ac0c7 100644
--- a/src/pmm.c
+++ b/src/pmm.c
@@ -58,6 +58,25 @@ const char *pmm_os_name(PmmOS os) {
     }
 }
 
+const char *pmm_detect_arch(void) {
+#if defined(_WIN32)
+    /* Windows: x64 vs arm64 (ARM64 / AMD64 env) */
+    const char *p = getenv("PROCESSOR_ARCHITECTURE");
+    if (p && (strcmp(p, "ARM64") == 0 || strcmp(p, "arm64") == 0)) return "aarch64";
+    const char *w = getenv("PROCESSOR_ARCHITEW6432");
+    if (w && (strcmp(w, "ARM64") == 0)) return "aarch64";
+    return "amd64";
+#elif defined(__aarch64__) || defined(__arm64__)
+    return "aarch64";
+#elif defined(__x86_64__) || defined(_M_X64)
+    return "amd64";
+#elif defined(__i386__) || defined(__i686__) || defined(_M_IX86)
+    return "x86";
+#else
+    return "any";
+#endif
+}
+
 static void mkdir_p(const char *path) {
     char tmp[1024];
     strncpy(tmp, path, sizeof(tmp) - 1);
diff --git a/src/pmm.h b/src/pmm.h
index c116e58..996bd40 100644
--- a/src/pmm.h
+++ b/src/pmm.h
@@ -45,6 +45,9 @@ const char *pmm_self_path(void);
 
 typedef enum { OS_WINDOWS, OS_LINUX, OS_MACOS, OS_UNKNOWN } PmmOS;
 
+/* CPU architecture name string: "amd64", "aarch64", "arm64", "x86", ... */
+const char *pmm_detect_arch(void);
+
 typedef enum { HOST_GITHUB, HOST_GITLAB, HOST_GITEA, HOST_FORGEJO, HOST_AUTO, HOST_UNKNOWN } PmmHost;
 
 PmmOS pmm_detect_os(void);