Triangle identification algorithm for star images has been widely used in attitude detection systems that take star sensor as navigation parts at present.However,its low characteristic dimensions lead to a higher redundancy and a lot of mistake identification. To improve the accuracy of triangle identification algorithm, a modified algorithm based on traditional one was proposed. By the proposed algorithm,the guide star pairs that meet interstellar angle threshold were recorded in a star matrix and the times appeared of the guide starts were counted simultaneously. According to the truth that each star must be attached to two sides of the triangle, the special star pairs that appear less than twice should be eliminated, then the guide stars for contructing triangles were searched from stars left in the star matrix. The algorithm takes the interstellar angle and relative magnitude of stars as the identification feature and also take the hashing search method into the star identification, therefore , it reduces the comparison times and increases the identification speed. Furthermore, it also decreases the capacity of guide star database.