Abstract: In the problem of smoothing, filtering and predicting matching data in aerospace measurement, matching data refers that velocity parameter is differential of position parameter. By using the prior information that measuring data are matching, the design of the polynomial least square filter is improved. The resulting smoothing filter equation processes position data and velocity data at the same time. Ratio of efficiency variance is also given. Because of using of prior information, the number of parameter to be estimated is reduced, and the parameter estimation accuracy is enhanced. Simulation results show that this method can improve the parameter estimation accuracy notably when target is maneuvering.