In order to solve the problems of unstable target acquisition, low tracking accuracy, etc., caused by line-of-sight jitter in the electro-optical precise tracking and pointing system on the moving platform, based on the thought of reference-light-based line-of-sight stabilization technology and optical inertial reference unit (OIRU), an improved fine-tracking control loop suitable for the compound-axis control is designed. And the series control of OIRU and the fine-tracking fast-steering mirror is realized. At first, in order to guarantee the realization of excellent fine-tracking control performances at the same time of the line-of-sight jitter compensation, a low-frequency error boost-frequency prediction function is established to satisfy the high frequency control sampling of the fine-tracking loop. And then, the fine-tracking control is realized by applying nonlinear proportional differential (PD) control algorithm based on extended state observer (ESO). At last, simulations are conducted to verify that the nonlinear PD controller can effectively improve the control performances of the fine-tracking system. In addition, the simulations show that the proposed improved fine-tracking control system can track different threat target trajectories accurately and has good anti-disturbance performance.