In order to recognize the type of aircraft in digital image fastly, an algorithm of aircraft recognition based on the structural feature points and affine transform is presented after the closed outline of an aircraft has been obtained. By using the symmetry of the aircraft to get the feature points and taking those points as matched points of two different images, the homogeneous matrix between the two images is calculated; then by transforming the outline of an aircraft in one image to the other image, the outlines of two aircrafts in the latter image is compared to judge whether the two aircrafts are the same type. The experimental results indicate that the recognition result can be given within 0.2 s,after the closed outline of aircraft is obtained,which can satisfy the C3I system requirements of high precision, rapid speed and stabilization.