Currently, the Kalman filter can only be applied to linear systems. The extended Kalman filter and unscented Kalman filter developed from the Kalman filter are widely used in solving nonlinear system filtering after strapdown seeker decoupling. With the development of precision guided weapons, the full strapdown seeker has been widely used in many guided weapons. This paper analyzes the working principle of the strapdown seeker, discusses the existing problems of the strapdown seeker, and further introduces the scheme of line of sight Angle rate extraction, and introduces the line of sight Angle rate estimation model through the relationship between coordinate conversion and angular rate decoupling. Through extended Kalman filter, unscented Kalman filter, The filtering principle is analyzed and the eye Angle rate is estimated and simulated by Matlab. The simulation results show that the accuracy of unscented Kalman filter is higher than that of extended Kalman filter, and the error is smaller. Compared with EKF, UKF is more suitable for filtering estimation of nonlinear system of strapdown seeker. Finally, by analyzing most of the existing filtering algorithms, the prospect of filtering algorithm research is put forward.