Abstract: The accuracy of fast steering mirror (FSM) can be improved by introducing filters in laser radar system under long distance conditions, but the delay problem brought about will affect the control performance of FSM. Therefore, in order to maintain the response speed while improving the tracking accuracy, a delay compensated linear quadratic regulator optimal control method was designed. The method constructed a discrete state-space model based on the dynamics and electrical model of FSM, and the optimal control was carried out by introducing a predictive compensator that approximated the first-order inertial link in combination with a state-feedback apparatus and a quadratic performance index. Experimental results show that in comparison with proportion integration differentiation (PID) control, the delay compensated linear quadratic regulator optimal control method improves the step time by 61.83%, the tracking accuracy in the X-axis direction by 50.92%, and that in the Y-axis direction by 29.98%, which can make the scanning imaging system obtain more accurate and reliable observation data.