Conventional DC excited oscillating wave is easy to form space charge on cable. In order to solve the hidden danger of cable damage caused by dc compression, a new structure of oscillating wave power supply is proposed. The compression process of capacitor serially connected oscillating wave circuit is analyzed, and then the Multisim software is used to simulate and combine the simulation data to determine the feasibility of its theory. Taking the 10kV cross-linked polyethylene cable in the laboratory as the research object, a capacitive serially connected oscillating wave experimental platform was designed and a new type of oscillating wave partial discharge experiment was carried out. The experimental results show that the new oscillating wave circuit can effectively avoid the space charge generated by the cable in the test process, and can effectively detect the partial discharge of defects in the cable, and can replace the traditional oscillating wave test method.