Line matching plays an important role in image registration, object recognition, and other applications. This paper presents an image registration algorithm based on space structure features of line. The four-parameter affine transformation model is used in coarse registration. The line matching problem is converted into a point-matching problem through construction of azimuth histogram which reflects the space structure features of line distribution in fine registration. The RANdom SAmple Consensus(RANSAC) method and parameter iteration consistency method are used to delete the error matching points. Experimental results show that the proposed algorithm is provided with high registration accuracy.