The automatic test system of relay protection equipment of intelligent substation is studied in order to detect the existing relay protection devices. In the test system, cloud storage and isolable technology are introduced, and the intelligent acquisition of relevant parameters of the protection device is obtained, and the test list is automatically generated. At the same time, it integrates the MMS protocol in the test system, which can realize real-time automatic test in the process of reading and writing protection setting value, setting up the test parameters, casting back device soft plate to match the current test project, and automatically complete the whole test process. The system fully improves the safety of secondary system, avoids the waste of manpower and material resources, effectively improves laboratory testing efficiency and on-site debugging efficiency, and reduces the time and expenditure of infrastructure and maintenance. So it is very important for the promotion and application of smart substation. This work is supported by Science and Technology Project of State Grid Jiangsu Electric Power Co., Ltd. (No. J2017036).