A sun tracking device comprises a light sensing module, a processing module, a control module, and a driving module. The light sensing module includes eight light sensors, a pole fixing portion, and a pole. The eight light sensors each have a light sensing surface. The pole fixing portion has a fixing surface. The eight light sensing surfaces and the fixing surface cooperatively form a 3×3 grid, and the fixing surface is in the middle of the grid. The pole extends from the fixing surface. The processing module is configured for determining the direction of the sun, and calculating a rotating direction and angle of the light sensing module. The control module is configured for sending out a rotating instruction. The driving module is configured for driving the light sensing module to rotate so that the sunlight perpendicularly shines onto the light sensing surface.