In image matching process, the affine transformation is difficult to avoid. In exiting algorithms, Scale Invarian Feature Transform(SIFT) has strong resistance to changes of scale, rotation, translation and illumination changes generated by affine transformation.However,when an image has a view angle change, especially large change,the SIFT is not satisfactory. This paper researches the principle of the SIFT and improves its matching function.The latitude and longitude of camera axis are simulated firstly, and then the images are matched by using the improved SIFT algorithm. Experiments show that the algorithm not only retains the original advantages of the SIFT algorithm, but also been robust to changes of the angle.It has achieved a complete anti-affine transformation. In conclusions, the proposed algorithm is more suitable to affine transformation, especially large angle changes, as compared with SIFT algorithm.