In consideration of the measurement time-delay and plant model uncertainty from signal processing and transmissiances in an imaging tracker,a robust Internal Model Control (IMC) strategy is designed for the opto-electronic tracking system. Firstly,the equations for designing the IMC controller based on the gain and phase margin specifications are given in detail. Then,the robust stability condition and the design criterion of parameters under plant/model mismatch are derived. Finally,a optimization method based on a quadratic cost function is introduced to adjust controller's parameters adaptively for improving the controlling ability and robust performance for the system. The experimental results in a four-axis opto-electronic tracking servo turntable indicate that the tracking precision is less than 1 mil,which is effective to overcome tracking errors caused by measurement time-delay and to ensure fast tracking for targets.