The invention relates to a retrosynthesis aperture radar image processing technology, and in particular relates to an ISAR image feature point extraction and matching method based on improved SIFT guidance. According to the method provided by the invention, on the basis of ensuring the advantages that the traditional SIFT is high in precision, and relatively high in rotation and scaling robustnessof the images, firstly, a small number of feature points with high matching precision is acquired via an improved SIFT matching algorithm, and then secondary matching is searched for guidance based on an image feature point conversion matrix, so that the number of matching points is further increased, the high precision complete matching between two ISAR image feature point sets is achieved, thatsituation that all extracted feature points reflect the target structure as complete as possible is ensured, and the important engineering application value is provided.