Mine power supply system played an important role in production. Status and protective measures of mine power supply system at home and abroad were studied in this paper, a system design based on single chip was put forward, which taking AT89C52 single chip as core with A / D conversion chip, LCD and multifunctional voice chip. It realized defensive function of overvoltage, overcurrent and short circuit. Meanwhile, stability and reliability of power supply system were improved, maintenance cost was decreased as well.