The high accurate control system for a diffraction grating ruling machine was designed by taking the S3C2440A as a control core to implement the real-time shows, real-time control and other functions. The S3C2440A micro controller was used to control a servo motor and a stepping motor to complete the indexing movement and the ruling movement of the grating ruling, the SiGNUMTM RELM straight line grating' feedback and PD plus feedforward control algorithm were taken to compensate the index error caused by the inertia and other reasons, then the indexing movement using PD plus feedforward control algorithm was simulated by MATLAB. Furthermore, the error caused by the out-of-step of stepping motor was compensated by the feedback of a RON225 incremental angle encoder, and the best speed of the indexing movement and the overshoot distance of the servo motor when it stopped were collected by the analysis and the process of the experimental data. Finally, the analysis on the controlling error was introduced, and how to improve the system in further was put forward.