With the acceleration of Chinese industrialization and the continue increasing demand for coal mine, more and more coal-mines use the 3.3kVvoltage level. So the probability of leakage failure occuring is greatly increased, and the lives of people and property safety is greatly threatened This paper simulates the common leakage fault types based on MATLAB/Simulink, gives the leakage protection measures, and designs the corresponding leakage fault protection device, the hardware diagram and protection program flow chart.