Abstract: For problems of poor electromagnetic immunity and weak load capacity of current intrinsically safe power supply, a high-performance mine-used intrinsically safe power supply was designed. The power supply is based on quasi-resonant flyback switching power supply and dual overvoltage and overcurrent protection, which can convert AC85-250 V wide input voltage into stable DC12 V/2 A output. The test results show that the power supply has small ripple, high efficiency and strong electromagnetic immunity, which meets intrinsic safety performance requirements of GB 3836.4-2010 Explosive Atmospheres Part 4: Equipment Protection by Intrinsic Safety "i".