An automatic leveling system includes a platform, a leveling device provided on the platform, a loading tray provided on the leveling device, three reflecting devices provided on the loading tray, an image acquisition device provided above the loading tray, a height positioning device provided on an end of the image acquisition device facing the loading tray, a light source configured to emit light, and a controller coupled to the image acquisition device. The height positioning device processes light emitted by the light source into three paths of light to the three reflecting devices. The three reflecting devices reflect the three paths of light. The image acquisition device acquires the three paths of reflected light into a light signal. The controller detects deflection values of the loading tray according to the light signal and controls the leveling device to level the loading tray.