In the integrated navigation system, the carrier phase has higher accuracy than the pseudo-range, but it has the problem of the solution of integer ambiguity. This paper proposes a GPS/INS integrated navigation algorithm based on the double-difference of time/inter-satellite with carrier phase. First, the algorithm is used to eliminate the influence of ambiguity by the simplified time-differenced technique. Then, aiming at the problem that the errors of the time differential carrier phase is accumulating with time, the pseudo-range/pseudo-range rate measurement are introduced to provide absolute positioning information for damping. It uses the intersatellite difference technique to eliminate the clock error and clock error drift of the receiver, and builds a new Kalman model with lower dimension. Through the simulation of the measured GPS data, it is found that the proposed method has higher accuracy than the classical pseudo-range method, and the positioning accuracy of the east, north, high is increased by 60.47%, 65.03%, 53.79%.