In promoting the construction of a smart substation, there is a problem that the application and popularization of key secondary equipment such as protection and monitoring device are affected by the lack of verification means for the time measurement accuracy of relay protection tester. Therefore a device for testing and calibrating the time measurement accuracy is developed. First, the disadvantages of the existing methods are analyzed, the overall idea of the time measurement accuracy test and calibration for the relay protection tester is proposed, and a design scheme is completed. Secondly, based on accurate time calibration of input data, precise time output control technology, high-precision acquisition and output of SV, a GOOSE and hard output signal are achieved. Finally, based on action event generation and accurate timestamp technology, a high-precision and wide-range simulation of common action time of a power system are realized. This is the reference error measured by the protective relay test, as the reference error of the tester. Test and engineering verification results show that the time accuracy, action time simulation and anti-interference ability of the latest developed device meet the standard requirements and application requirements. They effectively solve the industry problem that the time measurement accuracy of the relay protection tester cannot be tested and calibrated, and improve the test and calibration ability and efficiency. This work is supported by the National Natural Science Foundation of China (No. U1804252).