A method to fulfill a function of automatic test system of relay protection device is described by using Qt4 and Microsoft Visual Studio 2010. The system consists of tester, automatic testing software. Automatic test system can realize protection logic of relay protection test, the master function test and the value range detection main test items. It can realize the testing process visible, saving test data, test report generation. Using the feature word concept it solves the problem of test case reuse. Automatic test system has been well applied in the relay protection device in the process of research and development, improving greatly the testing efficiency and testing adequacy.