Localizing the iris preciously is a significant problem which becomes the fundamental preprocessing of iris recognition. This paper presents an improved inner and outer iris localization method. For the boundary of an iris closes to a circle and the pupil brightness distributes equably, this paper presents a geometrical method based on circle vertical bisector intersection points to localize iris inner boundary and the center of the circle. As the boundary of the iris and sclera is always blurry, the paper also proposes a method based on outer boundary details enhancement and finally the Hough transform operator to localize the outer boundary of iris. Contrastive experiments prove this arithmetic is stable, efficient and speedy.