The invention relates to a transformer substation process layer device testing tool, a wiring board assembly thereof and a wiring board. The transformer substation process layer device testing tool comprises a support, a wiring board assembly is arranged on the support, the wiring board assembly comprises the wiring board which is provided with an optical fiber connector matched with an Ethernet port on the process layer device, a pin matched with a plug-in type terminal on the process layer device, and at least two of butt joints abutting against and matched with the screw head of a screw fixed terminal on the process layer device, the connection between the test system and the process layer device is achieved through the connection between their respective plug-ins and the ports, and then the follow-up test of the process layer device is realized, the wiring mode can achieve the wiring and the disconnection in one step for different types of wiring ports, the simpleness and convenience are guaranteed, the testing efficiency is improved, the cost is saved, and the hidden danger caused by manual wiring faults to products can be reduced.