The invention provides a periodic test device for a pressurized water reactor nuclear power plant protection system, which comprises a real-time control system, and a computer in network connection with the real-time control system for executing a human-computer interaction function. The real-time control system is an embedded controller and comprises a central processor and multiple synchronous data communication channels, and the real-time control system is connected with a tested channel of the protection system via the synchronous data communication channels. When the test is executed, the computer provides a test signal and issues a test instruction, and the real-time control system injects the test signal to the tested channel of the protection system via the synchronous data communication channels, executes the test instruction issued by the computer, acquires a test result, and feeds the test result back to the computer. The test device also comprises a self-inspection and annual inspection device which periodically executes self-inspection on the real-time control system and annual inspection on precision verification of analog input and output channels.