In view of the current lack of debugging means for HVDC protection system, this paper proposes a single device function test method and a distributed system test method for HVDC protection system, and designs a combined/distributed new HVDC test device to realize the above two test methods. The HVDC test device includes management module, power amplifier module, switch input/output module and optical fiber ethernet module, fiber FT3 module, power module, etc.; every/each module includes internal bus interface, general power interface, external fiber interface, through the internal bus interface and general power interface, each module is combined in a chassis to form a combined test device, through the external fiber interface and general power interface to form a distributed test device. Combined test device is easy to carry, easy to store and manage, mainly for the function and performance test of single HVDC protection device, while distributed test device is mainly for the field distributed system test scenario. This flexible combination method not only reduces the cost and volume of test device, but also has rich interfaces and flexible use. Engineering practice shows that the device fully meets the requirements of HVDC protection Requirements of on-site maintenance and operation of maintenance system.