The utility model relates to an intelligent distribution terminal backup power supply system directly used in an environment at the temperature of minus 40 DEG C. The system is characterized in that a power supply linearly converts an external temperature signal into an electrical signal through a temperature sensor in a temperature acquisition circuit, and then feeds back the signal to a PWM control part; the PWM control part adjusts power change and outputs rectification filter according to the signal; for the condition of large-scale terminal disconnection, which is caused by the fact that a device backup power supply system of a distribution automation terminal cannot be normally started in northern and other alpine areas, a power supply management module of whole industrial design and a novel dairy body silicon battery are designed; an industrial chip with the high ability of low temperature resistance and composite silicon salt are used as electrolytes of the battery; the capacity of the battery is still above 80% at the temperature of minus 40 DEG C; and the service life is no less than 5 years when the system works in an outdoor environment at the temperature from minus 40 DEG C to 60 DEG C.