To improve the accuracy of the eyeball control on the screen and complete high-accuracy operation to mobile phones or computers, based on the principle that the focus of human eye in screen and the image point in retinal can determine a line through the center of pupil, and the screen's luminous contour reflects on the eyeball to form a rectangular outline, an eyeball control accuracy improvement method based on digital image processing was proposed. The relationship between the pupil center and the rectangular contour is the specific position of the human eye focus on the screen. Real-time video of the eyeball was obtained through a high-definition camera, then digital image processing technology was used to analyze and process each frame of image for obtaining the position coordinates of human eye focus on the screen. The calculated coordinates of each frame were output to the mouse cursor to track the focus of the eyeball, and the position was output to a controlled device with a screen via wireless technology to achieve eyeball control. Simulation results show that the average accuracy of eye control of the proposed mapping method achieves 0.7 degree.