To improve the autonomous navigation ability of navigation constellation, a kind of autonomous orbit determination technology based on a solar sail at an artificial Lagrange point is proposed for navigation satellite. Based on crosslink range observation, real-time position information provided by the solar sail is used to eliminate the error of autonomous orbit determination caused by the overall rotation and drift of the navigation constellation. Nonsingular orbit elements are chosen as state vector when the extended Kalman filter (EKF) is designed to fuse satellite dynamics model and two kinds of observation information to determine the orbit. International GNSS service (IGS) precise ephemeris of GPS constellation is adopted to validate the method. The results of simulation show that the proposed algorithm can not only ensure the long-term stability, but also provide higher precision of orbit determination compared with the approach of combining crosslink range observation with inter-satellite orientation observation.