The invention discloses a detection device with a power supply self-compensation function and a compensation method thereof. The compensation method comprises the following steps: detecting whether an external power supply is switched on or not; if the external power supply is switched on, judging whether the
power supply voltage of the external power supply is higher than the working
voltage threshold of the sensor unit through the low-
voltage detection circuit; if yes, the foot
voltage control switch is switched on, the under-
voltage control switch is not switched on, and an external power supply supplies power to the
detector detection part; if the voltage is lower than the threshold value, the undervoltage
control switch is conducted and the foot
voltage control switch is not conducted, the
energy storage unit charging and discharging management circuit supplies power to the
energy storage voltage detection circuit to enable the
energy storage unit power supply
control switch to be conducted, and the power is transmitted to the
detector detection component through the power
supply management circuit for automatic compensation power supply; and if the external power supply is not switched on, the external power supply control switch is not switched on, and the energy storage unit does not self-
discharge to supply power to the sensing unit of the
detector detection part. According to the invention, automatic compensation when power supply of the detector detection part is insufficient is realized.