A foveated rendering method of a Virtual Reality (VR) system based on monocular eyeball tracking is provided. A first monocular mapping position, corresponding to a monocular eyeball of a user, on a display screen of the VR system is obtained, and then an Inter Pupilary Distance (IPD) corresponding to a binocular pupil distance of the user is obtained, so as to calculate a second monocular mapping position, corresponding to the other monocular eyeball of the user, on the display screen of the VR system according to the IPD and the first monocular mapping position. Then, main rendering regions are determined by taking the first monocular mapping position and the second monocular mapping position as circle centers and preset thresholds as radiuses respectively. High-resolution main rendering is performed in the main rendering regions.