The research progress of the hybrid GNSS-terrestrial localization and its mathematical model are introduced firstly.The problem of filter divergence applying the augmented unscented Kalman filter to realize the GNSS-terrestrial localization is analyzed.In order to prevent the filter divergence,a cycle reset me-chanism for the state estimate variance matrix is adopted during the joint state estimation.The simulation results show that the proposed method could make the filter working steadily meanwhile improve the positioning accuracy.