The invention discloses a test bench of a fuel cell vehicle power system. The test bench comprises a mechanical transmission system, a fuel cell system, an electronic control system and a radiating system, wherein the mechanical transmission system comprises a motor, a gearbox, a flywheel and a dynamometer, and the motor, the gearbox, the flywheel and the dynamometer are sequentially and coaxiallyconnected; the fuel cell system comprises a fuel cell, an electric-energy distribution module and an electric-energy storage module, and the fuel cell, the electric-energy distribution module and theelectric-energy storage module are connected according to a real vehicle; the electronic control system comprises a vehicle control unit, a fuel cell control unit and a cell management system, and the vehicle control unit, the fuel cell control unit and the cell management system are connected according to the real vehicle; the radiating system comprises a fuel cell, an electric-energy storage module and a radiating fan of a motor, and the fuel cell, the electric-energy storage module and the radiating fan of the motor are arranged according to the direction of a radiating opening of the realvehicle. The test bench of the fuel cell vehicle power system has the advantages that integration of the whole fuel cell system is convenient, the running state of the vehicle power system under theworking condition is effectively verified, encountered problems are discovered in advance and solved, and test data is provided for vehicle control function development optimization, energy management, performance verification and sample-vehicle integrated development.