Abstract: A light sensing device for solar tracking system includes a light blocking plate, a light blocking cover, a light guiding element and a light sensor, wherein the light blocking cover comprises an elongate opening facing upward. The light guiding element comprises an elongate light receiving face and a light outputting face and the elongate light receiving face of the light guiding element is exposed to the elongate opening of the light blocking cover for receiving a light from outside. The light sensor is disposed next to the light guiding element to receive the light outputted from the light outputting face and generate an electric signal. The elongate light receiving face renders the light sensor sensitive to the incident angle of the light so as to improve the accuracy of solar tracking system.