An expanded solar alarm lamp includes a solar cell component, a solar battery, a main controller, a xenon tube lamp, a circuit board, and a PC housing. The solar battery is connected to the solar cell component for receiving solar energy from the solar cell component and storing the solar energy to a battery that supplies electric power to the alarm lamp. The main controller and xenon tube lamp are installed on the circuit board; the PC housing is used for wrapping the circuit board and installed at the top of a car body; the xenon tube lamp is for generating a warning light; and the main controller is for determining whether the electric power supply is provided by the solar battery which is the xenon tube lamp based on the current stored electricity of the solar battery. The invention improves the performance and function of the solar alarm lamp.