Abstract: With the aim to simplify the calibration process in the head-mounted gaze tracking system,a one-time calibration method was proposed,which was built upon the iris recognition system and did not require any extra hardware.At the first time when the user took on a head-mounted gaze tracking system,the camera calibration was conducted.The eye image used for the calibration was recorded with the corresponding user's ID information.In the subsequent usages,the system automatically recognized the user by the iris recognition.The eye position were extracted and compared with the one captured at the calibration stage.The new calibration parameters were able to estimate based on the relative rotation angle and offset between these two images.The experimental results demonstrated that this method was able to avoid conducting the cumbersome calibration process each time when the relative position of an eye and the camera was changed but without affecting system's performance.So it greatly simplified the calibration process,and reduced the complexity of the usage of the head-mounted gaze tracking system.