The invention discloses an LED street lamp energy-saving device. The device comprises a supporting rod, a control box is welded to the outer wall of one side of the supporting rod, a storage battery is welded to the inner wall of one side of the supporting rod, a switch and a sensor are sequentially welded to the inner wall of one side of the control box, and are connected through a wire, a light inductor is welded to the outer wall of the top of the supporting rod, a light receptor, an inductor and a signal processing device are arranged in the light sensor, and a lamp box connecting rod and a solar panel are sequentially welded to the outer wall of the side, away from the control box, of the supporting rod. According to the technology, the light sensor is used for replacing a timer, through the method, the control effect on the street lamp lighting time is better, the device is suitable in different seasons, the effect of lighting at night and lighting off at dawn can be achieved, a reflecting mirror is arranged in the lamp box, and can reflect light sent out by an LED lamp, the lighting effect can be met under the condition that a small number of LED lamps is used, and the resource use amount is effectively reduced.