Aiming at the application of X-ray detector in satellite autonomous navigation,a spacecraft autonomous celestial navigation method based on X-ray source/geocentric vector observation is proposed. The principle of X-ray source/geocentric vector autonomous navigation is studied and the autonomous navigation system scheme is presented. The system observation residual which is caused by X-ray source vector orientation error and Earth-central vector orientation error is theoretically analyzed,and then the residual is modeled as mitigable value. The satellite state model equation is established and the unscented Kalman filter (UKF) algorithm is applied to the autonomous navigation process. Navigation algorithm proposal is carried out considering the asynchronism of the observation period and the navigation period. Near earth satellite autonomous navigation simulation results verify the effectiveness of the proposed method.