In order to reflect the advantages of high informatization of smart substation, an automatic test system for relay protection equipment in smart substation is studied for intelligent relay protection device. Information fusion technology is introduced in the test process, which can automatically change test parameters, drop and retreat soft platen and write control words. And it can also automatically obtain the action information of secondary equipment, judge the correctness of secondary equipment response, and generate comprehensive test report meeting the requirements of the power industry, forming a complete closed-loop test. The application results show that the automatic test system optimizes the test process and provides a new test method that is not accessible to human, thus improving the test efficiency and accuracy. This work is supported by Science and Technology Project of China Southern Power Grid Company “Research on MMS In-the-loop Automatic Test Mode and its Application in the Periodic Inspection Process of Relay Protection” (No. 06062002018030101BD00086).