Through the improvement and reconstruction of cam X-C axis linkage machining model, the general compensation model of X-C axis linkage machining was established； by using the least square fitting to restore the data curve and get the regular output, and combined with the delay compensation mode, the online detection and compensation function of cam machining was realized. Therefore, it can solve the problem that the linear displacement and angular feedback cannot compensate synchronous error of the X-C axis linkage, so the influence of the X-C axis linkage synchronous error can be effectively reduced, the machining precision and quality of cam can be effectively improved，which provides a feasible scheme for the online detection compensation of cam machining.