In the mechanical compensation continuous zooming system, camcurve muff is the key part. The precision and surface quality of zooming cam slot and compensating cam slot have a great influence on the image. Thicken ruled surface mode was used to finish the modeling of cam slot, and tolerance control of matrix groups points was applied in fitting curve line. Using 4axis climbmilling tool path mode, the tool start point and retracting point were processed in a special method, the cam slot was accomplished. The experiment indicates the precision and surface quality of the cam slot are greatly improved.