The invention discloses a method for automatically testing a single board of a protective relay device. According to the method, a hook function is added in a program on a single board plug-in unit; and when a test program data packet is sent, the hook function can acquire the corresponding data packet and store the data packet in an executable RAM region. An application program can automatically jump to the RAM region to execute the test program and test whether the functions of the single board are normal or not; and after the single board is powered down and powered up again, the application program cleans up the RAM region data packet after self-checking the RAM, and the test program is automatically deleted. The method disclosed by the invention can bring conveniences for testing the single board of the protective relay device, reduce the single board debugging steps, and improve the production efficiency.