Abstract: In view of the limitations of fast and precise iris location，an algorithm for image segmentation based on curve fitting is proposed.The main technique of the algorithm is that off-line acquire Fourier descriptor of boundary，as standard curve，of the clear iris-image，then search and fit the boundary of aim-image through standard curve for accurately and fast estimating the position of iris.The experimental result indicates，the algorithm can steadily realize that the goal is cut apart and drawn，and possess better robustness.