The invention provides a periodic test system for protection systems for pressurized water reactor nuclear power plants. The periodic test system comprises an upper computer system and a lower computer system. Database in the upper computer system are managed, so that data required by tests can be provided; each channel test comprises at least one test, each test corresponds to a function module, the corresponding function modules are called when the channel tests are executed, then the data which correspond to the function modules and are required by the tests are called from the databases and are transmitted to the lower computer system via networks, and instructions for executing the function modules are transmitted to the lower computer system; the lower computer system comprises test items corresponding to the function modules of the channel tests, and the corresponding test items are executed when the instructions transmitted by the upper computer system are received by the lower computer system.