Abstract: Because GPS can not realize continuous and accurate position in the city and the vehicle dead reckoning system(DR) has the self-help in calculating the position,the state and measurement equations for the GPS/DR integrated system is proposed.Based on this.According to the different sampling frequency of GPS and DR,the technique of measurement in advance is introduced and used in the algorithm of GPS/DR integrated system,then the Kalman filtering equations are erected using the technique of measurement in advance,finally the above algorithm is validated by the practical dynamic experiment,and the corresponding conclusions are made.