An uninterrupted power supply UPS circuit, comprising: an alternating current input module, a positive Boost boost module, a negative Boost boost module, a battery, a first switch transistor, a second switch transistor, and a first thyristor; wherein the alternating current input module is configured to convert the mains into a direct current voltage; the positive Boost boost module, connected to the alternating current input module, is configured to boost the direct current voltage output by the alternating current input module in a positive half cycle of the mains; the negative Boost boost module, connected to the alternating current input module, is configured to boost the direct current voltage output by the alternating current input module in a negative half cycle of the mains; and the second switch transistor is configured to select to connect the alternating current input module and the battery to the positive Boost boost module or the negative Boost boost module; characterized in that a collector of the first switch transistor is electrically connected to a cathode of a first diode in the positive Boost boost module and one end of a first output filter capacitor in the positive Boost boost module, and an emitter of the first switch transistor is electrically connected to one end of a second inductor in the negative Boost boost module and a cathode of the battery; and an anode of the first thyristor is electrically connected to the other end of the second inductor in the negative Boost boost module, a cathode of a second diode in the negative Boost boost module, and an emitter of a fourth switch transistor in the negative Boost boost module, and a cathode of the first thyristor is electrically connected to an anode of the battery. an alternating current input module, a positive Boost boost module, a negative Boost boost module, a battery, a first switch transistor, a second switch transistor, and a first thyristor; wherein the alternating current input module is configured to convert the mains into a direct current voltage; the positive Boost boost module, connected to the alternating current input module, is configured to boost the direct current voltage output by the alternating current input module in a positive half cycle of the mains; the negative Boost boost module, connected to the alternating current input module, is configured to boost the direct current voltage output by the alternating current input module in a negative half cycle of the mains; and the second switch transistor is configured to select to connect the alternating current input module and the battery to the positive Boost boost module or the negative Boost boost module; characterized in that a collector of the first switch transistor is electrically connected to a cathode of a first diode in the positive Boost boost module and one end of a first output filter capacitor in the positive Boost boost module, and an emitter of the first switch transistor is electrically connected to one end of a second inductor in the negative Boost boost module and a cathode of the battery; and an anode of the first thyristor is electrically connected to the other end of the second inductor in the negative Boost boost module, a cathode of a second diode in the negative Boost boost module, and an emitter of a fourth switch transistor in the negative Boost boost module, and a cathode of the first thyristor is electrically connected to an anode of the battery.