Traditional firstorder extended Kalman filter algorithm is widely used in various types of shells extrapolation filter,and it requires continuous occupancy of radar’s time resource. The hybrid model Kalman Filter algorithm which is based on the Least Squares Filter and the EKF contrapose the mortar’s movement characteristics of the small initial velocity and big launch angle,using flexible segmented sampling,realize good extrapolation of mortar’s movement .The simulation show that,the algorithm has the similar accuracy to the EKF in different launch angle and azimuth and even better in high launch angle, takes less resources,has good realtime performance,and it is suitable for practical engineering.