The utility model relates to DC power supply based lithium iron phosphate battery auxiliary management device, which comprises a diode, a DC contactor, a DC current acquisition unit, a microprocessor and a battery, wherein one ends of the diode and the DC contactor, which are connected in parallel, are connected to the DC current acquisition unit, the other ends of the diode and the DC contactor, which are connected in parallel, are connected to an output terminal of the lithium iron phosphate battery auxiliary management device, the other end of the DC current acquisition unit is connected to an output terminal of the lithium iron phosphate battery auxiliary management device, the input end of the microprocessor is connected to the output end of the DC current acquisition unit, the input end of the DC current acquisition unit is connected to the battery and the DC contactor, the output end of the microprocessor is connected to the input end of the DC current acquisition unit, and the microprocessor is connected to a DC system general monitoring device and communicated with the DC system general monitoring device in a bidirectional mode. The service life of a lithium iron phosphate battery is prolonged and the performance of the lithium iron phosphate battery is improved through the auxiliary management device, thereby improving the reliability of DC power supply.