The performance of anti-disturbance is a key problem in the process of middle-convex and varying ellipse piston machining. In practical application, the system can easily trace external periodical signal off-load. But if anti-disturbance can not reach requirement, the capability of tracing reference signal will reduce severely to influence machining precision on-load. The disturbance restraint for varying load to linear servo drive system is studied in the paper and the disturbance of cutting force varying periodically is pointed out. A new control strategy integrates repetitive control with iterative learning control algorithm is proposed in order to reduce the influence of load disturbance to tool position. A new train of thought to improve middle-convex and varying ellipse piston machining precision is proposed in the paper.