This application discloses an eyeball tracking system and an eyeball tracking method thereof, and relates to the field of retinal projection technologies. The eyeball tracking system includes: an illumination light source, configured to transmit an illumination light ray to a beam scanner; the beam scanner, configured to project the illumination light ray onto an entrance pupil optical apparatus; the entrance pupil optical apparatus, configured to reflect, reproduce, or refract the illumination light ray, so that the reflected, reproduced, or refracted illumination light ray illuminates an eyeball; a photoelectric detector, configured to: collect a receive optical power value of an eyeball reflection light ray, and send the receive optical power value to a controller; and the controller, configured to: receive the receive optical power value sent by the photoelectric detector, determine, based on the receive optical power value, an optical power reference value that satisfies a specified functional relationship with the receive optical power value, and determine an eyeball line-of-sight direction that matches the optical power reference value as a current gaze direction of the eyeball based on a prestored one-to-one matching relationship between a plurality of eyeball gaze directions and a plurality of optical power reference values.
EYE TRACKING SYSTEM AND EYE TRACKING METHOD