The invention provides a meteor crater mismatching determination method based on ratio of shaded area to external-contour area, and relates to the technical field of image processing, solving the problem of mismatching of conventional meteor crater extracting and matching method. The meteor crater mismatching determination comprises the following steps in sequence: selecting a meteor crater pair from the meteor crater pairs which are given the matching; calculating the altitude angle Theta of the sun at the image shooting time based on the ephemeris; calculating the ratio SR of the shaded area to the external-contour area, from the three-dimensional topography, of the meteor crater according to the three-dimensional model of the meteor crater and the altitude angle Theta of the sun; calculating the ratio S' of the shaded area to the external-contour area, from the image shot during falling, of the meteor crater; and if the absolute value of SR-S' is more than a given threshold, determining that the selected meteor crater is subjected to mismatching. According to the meteor crater mismatching determination method based on the ratio of the shaded area to the external-contour area, the mismatched meteor crater is removed from the meteor crater pairs which are given the matching after the matching between the meteor crater in the image which is shot when a lander falls and the meteor crater in the planetary three-dimensional topography is accomplished, and thus the accuracy in matching of the meteor crater can be improved.