A method of identifying iris is provided. The method includes providing a plurality of incident lights entering an eye located at a reference position； setting a first, second and third reference points； forming a first, second and third measuring glint by the incident lights after the eye moves to a measuring position； capturing an eye image of the eye including a first, second and third measuring glint images and an iris image； analyzing a gray scale value of the eye image to obtain the positions of the first, second and third measuring glints； and calculating a variation of the distance between the first measuring glint and the second measuring glint, a variation of the distance between the second measuring glint and the third measuring glint to obtain an resolution variation of the iris image when the eye is located at the measuring position.
