A rapid iris localization algorithm based on image sampling was proposed. One point in the pupil was firstly detected in the sampled image. With this point as the initial one, the coarse edge points were detected, and then the inner iris edge could be located by the exact edge points extracted by gradient operator in the image with original resolution. The outer iris edge was located using Canny operator and Hough transform. Since the edges were extracted based on the sampled image, plenty of detailed boundaries such as iris texture were ignored, which reduced the outer disturbing boundaries and improved the real-time property of algorithm. The experiment results show that the algorithm achieves 99.47 % in accuracy and 0.162 s in speed. In comparison with other classical localization methods, the developed algorithm is much faster.