In order to improve the surface shape recovery accuracy of Ricky-Consens test under large F-number, a local sampling impact matrix method is proposed. The impact matrix is built according to the actual incident angle of each pixel point for the compressed ellipse patterns collected from an interferometer, and the surface error of the pixel point is recovered. The shape of flat mirror is obtained through this method traversing the entire mirror surface. The accuracy of local sampling impact matrix method is verified through simulation, and it is compared with the traditional impact matrix method in detail. The results show that compared with the traditional impact matrix method, the accuracy of local sampling impact matrix method is obviously improved in different aberrations of defocus, astigmatism, three levels of coma, three levels of astigmatism and three levels of spherical aberration. It is indicated that the local sampling impact matrix method is more suitable for the surface shape recovery Ritchey-Common test.