A new flexible feeding ECM machine has been presented in the paper. The rational optimization rules of cathode’s feeding are proposed. According to analysis of a three dimensinal complicated surface’s shaping process, the cathode’s feeding route is optimized. Instead of feeding at a constant angle the cathode in the paper can feed flexibly during the ECM process. Finally the analysis result of distribution of inter-electrode gap has shown that the optimized feeding route do help to improve the workpiece’s accuracy.