diff --git a/src/components/olmap/FlushingAnalysis/AnalysisParameters.tsx b/src/components/olmap/FlushingAnalysis/AnalysisParameters.tsx
index 9526e4f..b203a65 100644
--- a/src/components/olmap/FlushingAnalysis/AnalysisParameters.tsx
+++ b/src/components/olmap/FlushingAnalysis/AnalysisParameters.tsx
@@ -53,6 +53,7 @@ import {
   VALVE_STATUS_OPTIONS,
   validateValveSetting,
 } from "@components/olmap/core/Controls/valveControl";
+import { getValveListClassName } from "./analysisParametersLayout";
 
 export interface ValveItem {
   id: string;
@@ -582,7 +583,10 @@ const AnalysisParameters: React.FC<AnalysisParametersProps> = ({
             💡 点击地图上的阀门进行添加
           </Box>
         )}
-        <Stack spacing={1} className="max-h-50 h-48 overflow-auto">
+        <Stack
+          spacing={1}
+          className={getValveListClassName(valves.length)}
+        >
           {valves.map((valve) => {
             const settingValidation =
               valve.status === "ACTIVE"
diff --git a/src/components/olmap/FlushingAnalysis/analysisParametersLayout.test.ts b/src/components/olmap/FlushingAnalysis/analysisParametersLayout.test.ts
new file mode 100644
index 0000000..e1003bf
--- /dev/null
+++ b/src/components/olmap/FlushingAnalysis/analysisParametersLayout.test.ts
@@ -0,0 +1,13 @@
+import { getValveListClassName } from "./analysisParametersLayout";
+
+describe("getValveListClassName", () => {
+  it("uses compact height when no valves are selected", () => {
+    expect(getValveListClassName(0)).toBe("min-h-16 overflow-auto");
+  });
+
+  it("restores the fixed scroll region when valves are selected", () => {
+    expect(getValveListClassName(1)).toBe(
+      "max-h-50 h-48 overflow-auto",
+    );
+  });
+});
diff --git a/src/components/olmap/FlushingAnalysis/analysisParametersLayout.ts b/src/components/olmap/FlushingAnalysis/analysisParametersLayout.ts
new file mode 100644
index 0000000..fc14c78
--- /dev/null
+++ b/src/components/olmap/FlushingAnalysis/analysisParametersLayout.ts
@@ -0,0 +1,4 @@
+export const getValveListClassName = (valveCount: number): string =>
+  valveCount > 0
+    ? "max-h-50 h-48 overflow-auto"
+    : "min-h-16 overflow-auto";