A head-up display system includes a head-up display and an image detecting unit. The head-up display includes a first control unit, an image source, and an optical system. The first control unit is configured to correct an image signal. The image source is coupled to the first control unit and configured to output an image beam according to the corrected image signal. The optical system is disposed on a transmission path of the image beam. The image detecting unit is disposed at a side of the head-up display to detect a deviation angle of a user with respect to the head-up display. Here, the first control unit corrects the image signal in advance according to the deviation angle of the user with respect to the head-up display and according to an aberration generated by the optical system.