A method of authenticating a user based on iris recognition, the method comprising: acquiring an image of a user's left and right eyes; extracting a pupil image and an iris image from the image; obtaining a first iris feature by analyzing the iris image; obtaining a second iris feature by analyzing the iris image and the pupil image; generating a first similarity parameter by comparing an iris code corresponding to the first iris feature with a reference code included in prestored reference iris data; generating a second similarity parameter by comparing the second iris feature with a reference feature included in the prestored reference iris data, wherein the second iris feature includes information relating to geometric parameters for the user's pupil position and iris position; and obtaining (S305, S603) a similarity score by using the first similarity parameter and the second similarity parameter; and determining whether to approve user authentication based on the similarity score; wherein the generating of the first similarity parameter comprises: calculating a normalized Hamming distance HD Left for the left eye and a normalized Hamming distance HD Right for the right eye by comparing the iris code with the reference code; determining a bit number BitCount Left for the left eye used to calculate the normalized Hamming distance HD Left for the left eye and a bit number BitCount Right for the right eye used to calculate the normalized Hamming distance HD Left for the right eye; and generating the first similarity parameter based on the normalized Hamming distance HD Left for the left eye, the normalized Hamming distance HD Right for the right eye, the bit number BitCount Left for the left eye, and the bit number BitCount Right for the right eye. acquiring an image of a user's left and right eyes; extracting a pupil image and an iris image from the image; obtaining a first iris feature by analyzing the iris image; obtaining a second iris feature by analyzing the iris image and the pupil image; generating a first similarity parameter by comparing an iris code corresponding to the first iris feature with a reference code included in prestored reference iris data; generating a second similarity parameter by comparing the second iris feature with a reference feature included in the prestored reference iris data, wherein the second iris feature includes information relating to geometric parameters for the user's pupil position and iris position; and obtaining (S305, S603) a similarity score by using the first similarity parameter and the second similarity parameter; and determining whether to approve user authentication based on the similarity score; wherein the generating of the first similarity parameter comprises: calculating a normalized Hamming distance HD Left for the left eye and a normalized Hamming distance HD Right for the right eye by comparing the iris code with the reference code; determining a bit number BitCount Left for the left eye used to calculate the normalized Hamming distance HD Left for the left eye and a bit number BitCount Right for the right eye used to calculate the normalized Hamming distance HD Left for the right eye; and generating the first similarity parameter based on the normalized Hamming distance HD Left for the left eye, the normalized Hamming distance HD Right for the right eye, the bit number BitCount Left for the left eye, and the bit number BitCount Right for the right eye. calculating a normalized Hamming distance HD Left for the left eye and a normalized Hamming distance HD Right for the right eye by comparing the iris code with the reference code; determining a bit number BitCount Left for the left eye used to calculate the normalized Hamming distance HD Left for the left eye and a bit number BitCount Right for the right eye used to calculate the normalized Hamming distance HD Left for the right eye; and generating the first similarity parameter based on the normalized Hamming distance HD Left for the left eye, the normalized Hamming distance HD Right for the right eye, the bit number BitCount Left for the left eye, and the bit number BitCount Right for the right eye.