Abstract: In order to prevent the coal and gas outburst occurred, the paper had a study on the vibration, electric magnetic radiation and vadose variation mechanis m occurred when the expansion caused from the cracks in the coal mass as well as the expansion occurred from the cracks.Also from the coupling review of the vibrati on field, the electric magnetic field, the stress field and the vadose field, the paper had an analysis on the cause to occur the coal and gas outburst.The results showed that the coal and gas outburst occurred process would be results of the cracks occurred and rapid developed in the coal mass.During the crack occurred process, the re lated vibration field and electric and magnetic field would be inevitably occurred.The cracks occurred and expanded as well as the vibration field and the electric magne tic field could cause the variations of the stress field and the vadose field in the coal mass.The comprehensive effects of those fields would make the cracks of the gas content coal mass to be rapidly expanded and connected.Thus the great macroscopic cracks finally formed would cause the stability of the gas content coal mass to be suddenly lost and failure and could cause the coal and gas outburst occurred.Thus the comprehensive roles of the vibration field, the electric magnetic field and vadose field would finally cause the coal and gas outburst occurred.