Abstract: In order to reduce the estimation error covariance of geomagnetic navigation and improve the reliability and the stability of geomagnetic navigation,an integrated navigation algorithm based on three-axis magnetometer and gravity measurement is proposed which introduces gravity as new measure information into the geomagnetic navigation system.The algorithm uses the position and the velocity of the aircraft as state vectors to establish state equation,and the intensity vectors of the magnetic field and the gravity field as observation vectors to establish observation equation.A kind of federated filter is designed to fuse the measured information from three-axis magnetometer and gravity measurement.For both the state and the measurement equations of those two methods are nonlinear,the unscented Kalman filter(UKF) is used as the sub- filter to improve the accuracy.The simulation results show that the position estimation error of the method is less than 30 m and velocity estimation error is less than 5 m/s.Comparing with mono-geomagnetic navigation system and mono-gravity navigation system,the integrated navigation algorithm shows better convergence and reliability.