Abstract: In order to prevent and control the gas accident from No.3B seam in Chengshan Mine and to understand the gas deposit features of Chengshan Mine, a qualitative and quantitative combined method was applied to establish the mathematics model to study the geological structure, seam roof and floor lithology and seam depth affected to the gas deposit and to study the division and zone features of the coal and gas outburst danger.The results showed that the structure complicated regi on in No.3B seam of Chengshan Mine was a gas concentrated zone, the surrounding rock lithology of the seam roof and floor was hard and compact and would be favo rable to keep the gas.With seam depth increased, the gas content and the gas emission would be getting higher and higher and the gas content gradient would be 3.01 m3/ (t.hm) .In the deep depth, the gas pressure would be increased and the permeability of the surrounding rock would be reduced. Especially in the structure complicat ed zone, the seam coal would be failed seriously and the zone with seam gas pressure at 0.74 MPa could be set as an outburst danger zone.