Stray corrosion is an important factor affecting the precision electrolytic machining (PECM) accuracy of the blisk surface, and the auxiliary anode can effectively inhibit the stray corrosion of adjacent machined blades, thereby improving the machining accuracy of blades. In order to solve the problem that the narrow and twisted inter-blade channel of the blisk of small and medium-sized aero-engines leads to the difficulty of auxiliary anode design, an auxiliary anode structure design method was proposed, which realized the optimal design of the auxiliary anode by optimizing the feed path of the tool cathode. Results of the experiment research show that the auxiliary anode designed by this method can be fed to the starting position of the machining smoothly, and the surface of the machined blade is smooth, and there are no obvious traces of stray corrosion, which effectively improves the machining accuracy of the blisk.