diff --git a/s-day01/src/com/inmind/system06/SystemDemo15.java b/s-day01/src/com/inmind/system06/SystemDemo15.java
new file mode 100644
index 0000000..46acbea
--- /dev/null
+++ b/s-day01/src/com/inmind/system06/SystemDemo15.java
@@ -0,0 +1,37 @@
+package com.inmind.system06;
+
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.util.Date;
+
+/*
+System类获取当前系统时刻
+static long currentTimeMillis() 返回当前时间（以毫秒为单位）。
+
+作用：以毫秒级别测试一段代码的执行效率，Instant以纳秒级别测试代码的执行效率
+ */
+public class SystemDemo15 {
+    public static void main(String[] args) {
+        // 获取当前时间
+        Date date = new Date();
+        long now2 = System.currentTimeMillis();
+        LocalDateTime now = LocalDateTime.now();
+        Instant now1 = Instant.now();
+
+        System.out.println(date);
+        System.out.println(date.getTime());
+        System.out.println(now1.getNano());
+        System.out.println(now2);
+
+        System.out.println("------------以毫秒级别测试一段代码的执行效率------------");
+        long start = System.currentTimeMillis();
+        //测试500次打印消耗的时间（毫秒级）
+        for (int i = 0; i < 500; i++) {
+            System.out.println(i);
+        }
+        long end = System.currentTimeMillis();
+        System.out.println("打印消耗的毫秒值："+(end-start));
+
+
+    }
+}