Abstract: In order to reduce the influence of seeker's disturbance rejection rate (DRR) on the output line-of-sight(LOS) angular rate, an online inhibition method for DRR was proposed. Firstly, the transfer functions of different guidance signal extraction points were established based on the platform seeker. Subsequently, the disturbance torque was regarded as the interference angular acceleration and the finite-time sliding mode disturbance observer (SMDOB) was used to estimate it and compensate it into the control loop in real time, so that the additional LOS angular rate caused by the DRR was greatly reduced. The simulation results show that the designed SMDOB could quickly track the disturbance, which is convenient for online compensation and inhibition for LOS deviation caused by DRR. Adopting the proposed strategy, the LOS angular rate error caused by the interference is substantially eliminated, and the accuracy of the output LOS angular rate is improved, which is beneficial for precise guidance.