diff --git a/scripts/test_gui.py b/scripts/test_gui.py
index 2a0c38c..85c454c 100644
--- a/scripts/test_gui.py
+++ b/scripts/test_gui.py
@@ -200,6 +200,8 @@ class PhotomagneticGUI:
 
         self.worker = SerialWorker(self)
         self._monitor_after_id = None
+        self._last_temp_time = 0.0
+        self._temp_interval = 0.0
 
         self._build_ui()
 
@@ -312,6 +314,7 @@ class PhotomagneticGUI:
         self._disp_labels = {}
         entries = [
             ("Temperature", "--- °C", "temp"),
+            ("Sample Rate", "---", "sample_rate"),
             ("Heating State", "---", "heat_state"),
             ("Heating Temp.", "--- °C", "heat_temp"),
             ("Device ID", "---", "dev_id"),
@@ -341,6 +344,11 @@ class PhotomagneticGUI:
         log_frame = ttk.LabelFrame(right, text="Log", padding=4)
         log_frame.pack(fill=tk.BOTH, expand=True, pady=(4, 0))
 
+        log_toolbar = ttk.Frame(log_frame)
+        log_toolbar.pack(fill=tk.X, pady=(0, 2))
+        ttk.Button(log_toolbar, text="Clear", width=6,
+                   command=self._clear_log).pack(side=tk.RIGHT)
+
         self._log_text = scrolledtext.ScrolledText(log_frame, height=12, font=("Consolas", 9),
                                                     wrap=tk.WORD, state=tk.DISABLED)
         self._log_text.pack(fill=tk.BOTH, expand=True)
@@ -520,6 +528,13 @@ class PhotomagneticGUI:
         # ── 0x00 TEMP: 设备主动推送, 只更新 live value, 不输出 log ──
         if cmd == Cmd.TEMP:
             t = temp_from_data(data)
+            now = time.time()
+            if self._last_temp_time > 0:
+                self._temp_interval = now - self._last_temp_time
+                hz = 1.0 / self._temp_interval if self._temp_interval > 0 else 0
+                self._disp_labels["sample_rate"].configure(
+                    text=f"{self._temp_interval*1000:.0f}ms ({hz:.1f}Hz)")
+            self._last_temp_time = now
             self._disp_labels["temp"].configure(text=f"{t:.2f} °C")
 
         elif cmd == Cmd.GET_ID:
@@ -569,6 +584,11 @@ class PhotomagneticGUI:
         if 0 <= idx < len(self._ntc_labels):
             self._ntc_labels[idx].configure(text=f"{idx}:{temp:.1f}")
 
+    def _clear_log(self):
+        self._log_text.configure(state=tk.NORMAL)
+        self._log_text.delete(1.0, tk.END)
+        self._log_text.configure(state=tk.DISABLED)
+
     def _append_log(self, msg: str):
         self._log_text.configure(state=tk.NORMAL)
         self._log_text.insert(tk.END, msg + "\n")