Aiming at the mixed fault problems caused by outliers in GNSS measurements and at-mospheric density errors in spacecraft autonomous navigation,this paper proposes a robust fusion method suitable for suborbital spacecraft based on SINS/CNS/GNSS multi-source integrated navi-gation to improve the accuracy and robustness of the navigation system under fault conditions.The method,which uses two-factor equivalent weights to adjust the filter gain matrix in the SINS/GNSS subsystem,is able to mitigate the adverse effect of fault information on state estimation when using GNSS correlation measurements.In the SINS/CNS subsystem,this method uses SINS positioning information to design an inertial-assisted RCNS fault diagnosis algorithm,the al-gorithm can effectively detect and isolate the navigation fault caused by the atmospheric density er-ror.Simulation is performed on a scenario containing the above fault information,and the experi-mental results show that the proposed algorithm can effectively control the effects of GNSS meas-urement anomalies and RCNS positioning faults on navigation results.Under fault conditions,the positioning accuracy can be controlled within 70 m,the velocity accuracy is less than 0.2 m/s,and the attitude accuracy is within 10 arc seconds.