Abstract: A safety helmet includes a helmet body, a solar panel on the surface of the helmet body, a headlight at the front side of the helmet body, a warning signal light at the rear side of the helmet body, a control circuit and a rechargeable battery on the inside of the helmet body, and a switch on the outside of the helmet body. When the switch is off, electric energy generated by the solar panel is stored in the rechargeable battery subject to the control of the control circuit; when the switch is on, the loop of the control circuit and the headlight and the warning signal light is closed, causing the headlight to emit light for illumination and the warning signal light to flash for giving a visual warning signal to vehicles from behind to assure safety when riding a bicycle or working at night.