Abstract: The paper introduced working principle,design of hardware and software of a digitized mine-used intrinsically safe UPS. Because the environment of coal mine is bad, double overcurrent protection and overvoltage protection for the UPS,overdischarge protection of battery were designed. The UPS can output four kinds of different voltage to meet electrical equipment according to user’s request. By digitized control of the power supply, the circuit is more simple, the function is more flexible, so it has higher value of(applicatio