This invention relates to a device for protecting rechargeable power supply of electronic cigarette. Wherein such device comprises a rechargeable power supply module, a microcontroller, a semiconductor switch and an interface module configured to connect a charging unit. The interface module comprises a first charging terminal and a second charging terminal. The microcontroller comprises an input end and an output end. The power supply module is connected to the microcontroller and supplies electric power to it. The input end and the output end of the microcontroller is connected to the interface module and the semiconductor switch respectively, and the microcontroller detects a voltage signal of the first charging terminal, judges whether an electric level of the voltage signal is positive or negative and sends a control signal to the semiconductor switch for controlling the semiconductor switch to be ON or OFF.