In the baseband signal processing of high precision GPS receiver, the measurement accuracy of carrier phase smoothing pseudo-code measurement is greater than that of pseudo-code measurement. The traditional phase-smoothed pseudo-range algorithm is suitable for the condition that the number of smoothing epochs is not too great, but this will not hold true in the application situation of the short time multi-epoch smoothing. So the deficiency of the traditional phase-smoothed pseudo-range algorithm is analyzed under the condition of smoothing epochs increased. The complementary Kalman filtering is then employed as a novel smoothing algorithm in comparison with the traditional one, and the corresponding mathematical analysis of complementary Kalman filtering is provided, the feasibility of the algorithm is also analyzed. The simulation results show that because the influence of all relevant errors is taken into account in the complementary Kalman filtering, its smoothing precision is higher than that of the traditional one when the number of smoothing epochs exceeds 500.