Aimed at the problems of noise influence, high time consumption and bad adaptive performance for iris localization, a rapid iris localization algorithm based on the method of iterative pixel ratio to cirque area is proposed. The proposed method is composed of 3 parts: cutting iris image, coarse localization by circle detection of the Hough transformation and the precise localization by an integrodifferential operator. The methods of cutting the iris image, image sampling, iterative pixel ratio to cirque area, rapid circle detection of the Hough transformation and the layered localization theory are used to improve the algorithm speed. The method of iterative pixel ratio to cirque area is put forward to reduce the radius range, and the morphological method is used to eliminate the pupil faculae. The threshold of pupil segmentation,small-range candidates of circle centre and radius, etc. are all obtained by the computation with good adaptive performance. Finally,four iris databases are applied in the experiments, and experimental results are compared with other algorithms. The results show that the accuracy of the proposed algorithm is 97.75%～99.07% and the time consumption is 52.847～158.502 ms. The experiments prove that the proposed method is a robust, rapid, adaptive iris localization algorithm with good comprehensive performance.