Abstract: Aiming at the problems exiting in protection system of low-voltage distribution network in coalmine,a centralized control method and several leakage judge algorithms were put forward.Upon improving the traditional leakage protection algorithms,the accuracy of leakage judging was improved.Based on the ARM core of STM32 processor,a new selective leakage protective device was studied and designed.It had been demonstrated the device responded fast and reliably which improved the stability of the power network.