For the feature point matching of SAR images used in navigation system, a feature point extraction approach is proposed based on Facet model.Firstly, the image intensity surface is well fitted through the Facet model.Then the second-order directional derivative of the center point of the fitting surface is calculated out, and the point whose second-order directional derivative is less than zero is taken as the potential feature point.Through normalization of absolute values for maximum values of the potential feature points and local non-maxima suppression, the feature points are obtained.Experimental results show that the proposed algorithm can successfully detect the feature point, and the real-time performance of the algorithm is better than that of the traditional SIFT algorithm.