I#, II# and III# coal seams of Pingzhai coal mine in Guizhou Province are t as the research objects. The potential danger of the coal seams is judged comprehensively through situ measuring gas pressure, observing the coal failure type, determining the initial speed of gas diffusion, strength coefficient of coal sample of coal seams and coal firmness coefficient with expansion energy of initial releasing gas. The testing result shows that the gas pressures in I#, II# and III# coal seams of Pingzhai coal mine are less than the critical value of 0.74 MPa which is defined by Coal and Gas Outburst Prevention and Control Regulation, but the expansion energy of initial releasing gas of coal sample is more than the critical value of 42.98 MJ/g. So the conclusion that the three coal seams are outburst risk seam can be determined comprehensively.