Abstract: We propose an autonomous navigation scheme based on optical navigation and inertial measurement unit(IMU) for lunar soft landing. In order to remove the accumulation errors of IMU, we use the on-board optical measurement information of pre-selected feature point to obtain relative position of the probe. Then, based on those optical information and the output trajectory of IMU navigation, the amendments of IMU navigation are completed by the multi-model adaptive filtering. In addition, the observability of entire navigation system is analyzed. Finally, the feasibility of the proposed autonomous navigation scheme is confirmed by numerical simulation.