A method of identifying iris includes: providing incident beams entering an eye locating at a reference position； setting a first, a second and a third reference point for locating the eye at the reference position； forming a first, a second and a third measuring glint by the incident beams after the eye moves from the reference position to a measuring position, and positions of the first, the second and the third measuring glint corresponding to the positions of the first, the second and the third reference point； capturing an eye image including a first, a second, a third measuring glint image and an iris image； comparing the gray scale value with a threshold gray scale value to obtain the positions of the first, the second and the third measuring glint； and calculating a first and a second variation to obtain an resolution variation of the iris image.
