Abstract: A testing system for modular multi-level converter HVDC flexible valve control equipment has been designed, which consists of simulation device for pole control, main circuit signals generator for converter stations, simulation device for valve sub-module and background monitor. This testing system can carry out the basic functional testing, including capacitor voltage reading and valve status monitoring, voltage sharing control, sub-module fault processing logic, valve control device fault processing logic and analog signal acquisition, of the modular and multilevel HVDC Flexible valve control device without the pole control system and converter valve. And it can meet the testing requirement of MMC HVDC flexible valve control device with different voltage classes or transmission capacity, by just adjusting the interface numbers of the simulation device for valve sub-module. A MVCE300 valve control device was tested and the testing result shows that the testing system can meet the testing need of modular multi-level converter HVDC flexible valve control equipment.