A removable multi-function hydraulic power supply unit was developed for the hydraulic equipment to enhance the ability of maintenance support in a domestic wind tunnel，and simulation analysis and field debugging were carried out. It could be used as an emergence power supply at the failure of the formal ones with the capacity of flexible movement and quick docking to the structure and control unit; it could be used as hydraulic test stand to provide the load test for the cylinder. Compared with conventional ones, the designed hydraulic power supply unit has the advantages of loading oil cylinder active position control and active oil filling, which provides reference for similar mobile oil source design.