A method for testing the accuracy of real time clocks is disclosed. The method includes the steps of: setting test parameters for testing the accuracy of real time clocks (RTCs), the test parameters comprising a test time length, a test time sampling interval, and an acceptable margin; synchronizing the time of an RTC IC and an RTC to be tested via a UUT; reading a current time of the RTC IC and the RTC via the UUT at each test time sampling interval; calculating a time difference between the current time of the RTC IC and the RTC via the UUT, and measuring whether the absolute value of the time difference is less than the acceptable margin; detecting whether the test time length is over; repeating the test process if the test time length is not over, or outputting test pass information if the test time length is over. A related system is also disclosed.