Abstract: An integrated GPS/DR Kalman filter which combines GPS pseudo-range,pseudo-range rate and DR raw data is designed.A field car-borne test has been carried out to compare and analyze the precision of the following three modes:GPS/DR loosely coupled module,pseudorange-based tightly module and GPS/DR tightly coupled module based on both pseudo-range and pseudo-range rate.The final results show that,compared with the loosely coupled integrated navigation system,GPS/DR tightly coupled integrated navigation system has made full use of the original information of GPS and DR,multiplied the observable measures,intensified the kalman filter tracking precision and improved the reliability and stability of the combined navigation system.