A three-dimensional (3D) image rendering method for a heads-up display (HUD) system including a 3D display apparatus and a catadioptric system is provided. The 3D image rendering method includes determining optical images corresponding to both eyes of a user by applying, to each of the positions of the eyes, an optical transformation that is based on an optical characteristic of the catadioptric system, and rendering an image to be displayed on a display panel included in the 3D display apparatus, based on a position relationship between the optical images and the display panel.