An autonomous optical navigation scheme for probes landing on small body is presented.The image coordinates of three pre-selected fixation-points (FPs) are obtained by using an optical navigation camera.And the distance from probes to each FP is measured using a laser range finder.Relative position for probes is acquired from three image coordinates and the distance.The real-time orbit for probes is determined by using the extended Kalman filter.The effectiveness of the scheme is validated using digital simulations.And the influence of the navigation precision upon the small body model error for small body is analyzed by simulations

under the certain sensors precision circumstance.