The invention belongs to the field of vehicle-mounted electronic devices, and discloses a 3D image correction method of a head up display. The correction method comprises steps of respectively converting a left eye source image or a right eye source image into a left eye predistortion image and a right eye predistortion image, wherein the image matrix T2 of the left eye predistortion image and the right eye predistortion image equals beta0 * T0/beta, wherein the beta is the system imaging magnifying power and is a matrix, and the T0 is the image matrix of the left eye predistortion image and the right eye predistortion image; outputting the left eye predistortion image and the right eye predistortion image at different time via a 3D image generator; and forming a distortion-free left eye image and a distortion-free right eye image via an imaging system. According to the invention, the left eye predistortion image and the right eye predistortion image can be obtained via the above formula and then output at different time by the 3D image generator; after the left eye predistortion image and the right eye predistortion image pass through the imaging system of the head up display, distortion-free left and right eye images are respectively formed; the left eye image is corrected without deformation accumulation; and image quality is high.