diff --git a/os/src/syscall/mod.rs b/os/src/syscall/mod.rs
index f0159c2..d29ad2c 100644
--- a/os/src/syscall/mod.rs
+++ b/os/src/syscall/mod.rs
@@ -30,7 +30,7 @@ pub fn syscall(syscall_id: usize, args: [usize; 3]) -> isize {
         SYSCALL_WRITE => sys_write(args[0], args[1] as *const u8, args[2]),
         SYSCALL_EXIT => sys_exit(args[0] as i32),
         SYSCALL_YIELD => sys_yield(),
-        SYSCALL_GET_TIME => sys_get_time(),
+        SYSCALL_GET_TIME => sys_get_time(args[0] as *mut TimeVal, args[1]),
         SYSCALL_SBRK => sys_sbrk(args[0] as i32),
         SYSCALL_MMAP => sys_mmap(args[0], args[1], args[2]),
         SYSCALL_MUNMAP => sys_munmap(args[0], args[1]),
diff --git a/os/src/syscall/process.rs b/os/src/syscall/process.rs
index dd873bf..a0ca421 100644
--- a/os/src/syscall/process.rs
+++ b/os/src/syscall/process.rs
@@ -3,7 +3,7 @@
 use crate::config::PAGE_SIZE;
 use crate::mm::{MapPermission, VPNRange, VirtAddr};
 use crate::task::{change_program_brk, create_new_map_area, exit_current_and_run_next, get_current_task_page_table_entry, suspend_current_and_run_next, unmap_virtual_page};
-use crate::timer::get_time_ms;
+use crate::timer::get_time_us;
 
 /// task exits and submit an exit code
 pub fn sys_exit(exit_code: i32) -> ! {
@@ -18,9 +18,24 @@ pub fn sys_yield() -> isize {
     0
 }
 
+#[repr(C)]
+#[derive(Debug)]
+pub struct TimeVal {
+    pub sec: usize,
+    pub usec: usize,
+}
+
 /// get current time
-pub fn sys_get_time() -> isize {
-    get_time_ms() as isize
+pub fn sys_get_time(ts: *mut TimeVal, _tz: usize) -> isize {
+    let us = get_time_us();
+    unsafe {
+        *ts = TimeVal {
+            sec: us / 1_000_000,
+            usec: us % 1_000_000,
+        };
+    }
+    0
+    -1
 }
 
 /// change data segment size
diff --git a/os/src/timer.rs b/os/src/timer.rs
index 1948c6a..8ddca7c 100644
--- a/os/src/timer.rs
+++ b/os/src/timer.rs
@@ -6,16 +6,23 @@ use riscv::register::time;
 
 const TICKS_PER_SEC: usize = 100;
 const MSEC_PER_SEC: usize = 1000;
+const MICRO_PER_SEC: usize = 1_000_000;
 
 pub fn get_time() -> usize {
     time::read()
 }
 
 /// get current time in microseconds
+#[allow(unused)]
 pub fn get_time_ms() -> usize {
     time::read() / (CLOCK_FREQ / MSEC_PER_SEC)
 }
 
+/// get current time in us
+pub fn get_time_us() -> usize {
+    time::read() / (CLOCK_FREQ / MICRO_PER_SEC)
+}
+
 /// set the next timer interrupt
 pub fn set_next_trigger() {
     set_timer(get_time() + CLOCK_FREQ / TICKS_PER_SEC);
diff --git a/user/src/bin/03sleep.rs b/user/src/bin/03sleep.rs
index 7e43d9c..d98c660 100644
--- a/user/src/bin/03sleep.rs
+++ b/user/src/bin/03sleep.rs
@@ -6,13 +6,19 @@ extern crate user_lib;
 
 use user_lib::{get_time, yield_};
 
+/// 正确输出：（无报错信息）
+/// get_time OK! {...}
+/// Test sleep OK!
+
 #[no_mangle]
 fn main() -> i32 {
-    let current_timer = get_time();
-    let wait_for = current_timer + 3000;
+    let current_time = get_time();
+    assert!(current_time > 0);
+    println!("get_time OK! {}", current_time);
+    let wait_for = current_time + 3000;
     while get_time() < wait_for {
         yield_();
     }
     println!("Test sleep OK!");
     0
-}
+}
\ No newline at end of file
diff --git a/user/src/bin/03sleep1.rs b/user/src/bin/03sleep1.rs
new file mode 100644
index 0000000..23b8060
--- /dev/null
+++ b/user/src/bin/03sleep1.rs
@@ -0,0 +1,22 @@
+#![no_std]
+#![no_main]
+
+#[macro_use]
+extern crate user_lib;
+
+use user_lib::{get_time, sleep};
+
+#[no_mangle]
+pub fn main() -> i32 {
+    let start = get_time();
+    println!("current time_msec = {}", start);
+    sleep(100);
+    let end = get_time();
+    println!(
+        "time_msec = {} after sleeping 100 ticks, delta = {}ms!",
+        end,
+        end - start
+    );
+    println!("Test sleep1 passed!");
+    0
+}
\ No newline at end of file
diff --git a/user/src/lib.rs b/user/src/lib.rs
index 6351f57..9d39c52 100644
--- a/user/src/lib.rs
+++ b/user/src/lib.rs
@@ -20,6 +20,19 @@ fn main() -> i32 {
     panic!("Cannot find main!");
 }
 
+#[repr(C)]
+#[derive(Debug, Default)]
+pub struct TimeVal {
+    pub sec: usize,
+    pub usec: usize,
+}
+
+impl TimeVal {
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
+
 use syscall::*;
 
 pub fn write(fd: usize, buf: &[u8]) -> isize {
@@ -32,7 +45,11 @@ pub fn yield_() -> isize {
     sys_yield()
 }
 pub fn get_time() -> isize {
-    sys_get_time()
+    let time = TimeVal::new();
+    match sys_get_time(&time, 0) {
+        0 => ((time.sec & 0xffff) * 1000 + time.usec / 1000) as isize,
+        _ => -1,
+    }
 }
 
 pub fn sbrk(size: i32) -> isize {
@@ -46,3 +63,10 @@ pub fn munmap(start: usize, len: usize) -> isize {
 pub fn mmap(start: usize, len: usize, prot: usize) -> isize {
     sys_mmap(start, len, prot)
 }
+
+pub fn sleep(period_ms: usize) {
+    let start = get_time();
+    while get_time() < start + period_ms as isize {
+        sys_yield();
+    }
+}
\ No newline at end of file
diff --git a/user/src/syscall.rs b/user/src/syscall.rs
index 12a1662..474684c 100644
--- a/user/src/syscall.rs
+++ b/user/src/syscall.rs
@@ -1,12 +1,15 @@
 use core::arch::asm;
 
+use crate::TimeVal;
+
 const SYSCALL_WRITE: usize = 64;
 const SYSCALL_EXIT: usize = 93;
 const SYSCALL_YIELD: usize = 124;
 const SYSCALL_GET_TIME: usize = 169;
+const SYSCALL_GETTIMEOFDAY: usize = 169;
 const SYSCALL_SBRK: usize = 214;
-pub const SYSCALL_MMAP: usize = 222;
-pub const SYSCALL_MUNMAP: usize = 215;
+const SYSCALL_MMAP: usize = 222;
+const SYSCALL_MUNMAP: usize = 215;
 
 fn syscall(id: usize, args: [usize; 3]) -> isize {
     let mut ret: isize;
@@ -34,8 +37,8 @@ pub fn sys_yield() -> isize {
     syscall(SYSCALL_YIELD, [0, 0, 0])
 }
 
-pub fn sys_get_time() -> isize {
-    syscall(SYSCALL_GET_TIME, [0, 0, 0])
+pub fn sys_get_time(time: &TimeVal, tz: usize) -> isize {
+    syscall(SYSCALL_GETTIMEOFDAY, [time as *const _ as usize, tz, 0])
 }
 
 pub fn sys_sbrk(size: i32) -> isize {