Abstract: Based on the surface electric potential experimental system of coal under loaded breaking,the variation law and grey- catastrophe characteristics of electric potential signals are tested and analyzed during loaded breaking of different coal samples under different gas pressure. The result shows that the breaking of gas- bearing coal owing to the combination effect of load and gas. The erosion effect of high pressure gas promotes the breaking of coal,which leads to higher electric potential signal. B ecause when coal samples under loaded breaking,the high pressure gas will wedge into the newly formed crack and accelerate the breaking of coal,thereby generates high er electric potential intensity,and the electric potential intensity has positive proportional relationship to gas pressure. The electric potential signal and grey- catastrophe mo del of gas- bearing coal under breaking is built,the electric potential and load catastrophe laws of gas- bearing coal under breaking are analyzed,using electric potential an d grey- catastrophe discriminant of load indicating three states such as damage accumulation,failure critical and instability fracture in the process of gas- bearing coal brea king is found. There are obvious precursor characteristics in the grey- catastrophe laws of electric potential signal for gas- bearing coal under breaking.