The invention relates to a solar protection storage battery under-voltage circuit and a protection method thereof. The circuit comprises a photovoltaic panel, a storage battery, a selection circuit, a power circuit, a main control circuit and a logic OR gate circuit, wherein the photovoltaic panel is used for providing power and outputting voltage; the storage battery is used for providing power and outputting voltage; the selection circuit is used for selecting higher voltage conduction and outputting conduction voltage when the photovoltaic panel and the storage battery simultaneously supply the power; the power circuit is used for receiving the conduction voltage output by the selection circuit and outputting the supply voltage and operating voltage used by load; the main control circuit is used for receiving the supply voltage output by the power circuit and outputting level signals; the logic OR gate circuit is used for receiving a level signal obtained by comparing the output voltage of the photovoltaic panel with reference voltage, an output level signal of the storage battery and an output level signal of the main control circuit, carrying out OR gate calculation on the three level signals and outputting control signals to control operation and failure of the power circuit. The solar protection storage battery under-voltage circuit is low in cost; the service life of the battery is prolonged; the power efficiency is improved; and a solar dormancy and wake-up circuit can be used.