A solar tracking device for solar panel includes a barrel body, a light transmitting unit, a projecting unit, a photosensor unit, and a lens. The light transmitting unit is disposed at a first end of the barrel body oriented toward the sun. The light transmitting unit has a light-transmittable crossing point provided at a center thereof. The projecting unit is an opaque member arranged between the first end and a second end of the barrel body. The photosensor unit is arranged to one side of the projecting unit, so that the projecting unit is located between the light transmitting unit and the photosensor unit. The photosensor unit has a locating center preset at a center of the projecting unit. The lens is arranged between the projecting unit and the photosensor unit. The barrel body is a telescopic barrel enabling the solar tracking device to switch between different operating angle modes.