As power transmission device, copper waveguide’s transmission performance is directly affected by silver electroplating quality in its cavity. If traditional electroplating process is used, it is difficulty to achieve uniform silver electrodeposit in the cavity of complicated copper waveguide. From the aspect of the product’s structure design and machining technics, the some key factors which have effects on electroplating quality of the cavity of complicated copper waveguide were analyzed. In addition, combining with some methods about process control of surface processing, appending of assistant anode, improving of electroplating technics, the solution on improving electrodeposit quality of the waveguide’s cavity was proposed.