A ball bar control device based on infrared sensors for range finding and a servo steering engine is mainly composed of two infrared sensors, a main body support, a control panel, two small balls, and a servo steering engine power supply system. The ball bar control device controls positions of the small balls on rods through given devices. Firstly, the position of the small ball on the mechanism lower part is acquired through one infrared sensor. Then, a control circuit acquires the real position of the small ball on the upper part through the measurement of the other infrared sensor. The deviation is then calculated. A control instruction for controlling the servo steering engine is then obtained by using control algorithm. The steering engine is then driven to adjust the angles of the rods so as to make the small balls move to designated positions under the effects of gravity. The ball bar control device which has a simple and feasible structure can accurately and rapidly control positions of the small balls. Meanwhile, the ball bar control device is low in cost.