According to the problem of disturbance rejection rate(DRR) with strapdown imaging seeker, the transfer functions of DRR due to different scale and dynamic error between detector and angular rate gyro were established. With Routh criteria and coefficient freezing method, the stable region of guidance system with disturbance rejection rate parasitic loop(DRRPL) was analyzed, the value range of scale error and dynamic error under different non dimensional time was presented. The effect on guidance accuracy of DRR was studied by adjoint method. The research can provide technology reference to the guidance and control system design of strapdown guided weapons, more attention should be paid on the positive feedback situation of DRR.