Crypt texture is an important feature texture on iris surface. For visible light iris image, how to extract the crypt texture fast and accurately without being influenced by the interference factor, such as eyelashes, eyelids, light spot and uneven illumination is still a challenging task. In order to solve this problem, a visible light iris crypt texture detection method based on morphology and support vector machine (SVM) is proposed in this paper. Firstly, the method combining grayscale morphology and twovalue morphology is applied to extract all the target textures in the iris image; and then, the regiongrowing method is used to locate all the target textures and calculate their corresponding feature vectors; at last, SVM and the method defining constraint condition are applied to extract the final crypt textures. Experiment results show that the proposed method can overcome the interference of light spot and etc., and is superior to other methods in terms of crypt texture detection rate.