The invention provides a lithium battery MCU power supply protection circuit, which is characterized by comprising an activation module, a charging isolation module, a power supply module, a self-locking module and a control module, wherein the control module comprises an MCU; the activation module comprises an activation switch K1, a diode D6, a diode D5, a diode D3, an MOS transistor Q1, a resistor R5, a resistor R3 and a capacitor C1; the activation switch K1, the diode D6, the resistor R5, the diode D5 and the capacitor C1 are connected with each other in series and then connected with an S electrode of the MOS transistor Q1; the other end of the capacitor C1 is connected with a G electrode of the MOS transistor Q1; and the diode D3 and the resistor R3 are connected in parallel at two ends of the capacitor C1. The lithium battery MCU power supply protection circuit is reasonable in design, is very low in power consumption, and does not directly affect the user experience and the cycle service life of a lithium battery.