In order to resolve the problems of easily interfered and unstable GPS signal, this paper puts forward the INS/GPS integrated navigation method and uses hardware circuit to verify the method. With given INS error model, it designs Kalman filter based on INS/GPS integrated navigation system, which takes posture, speed and position error as state variables. The paper takes east, north and vertical direction velocity error of INS and GPS outputs as the combination filter observation scheme. It uses simulation and experiments to analyze system precision and prove that this scheme is feasible. Then it can also realize the real-time filtering calculation, and meet the demand of navigation accuracy.