Abstract: Based on the 3215 mechanized caving face in Wangpo gassy coal mine, it analyzed the methane drainage mechanism of mining crack field，and obtained the width of working face plastic zone, the distribution characteristics of overlying strata cracks, and the spatial position of gob area “O” rings by UDEC numerical simulation and theoretical calculation. Based on this, it also confirmed methane drainage design parameters of the pre-pumping drilling in coal seam, the high borehole along roof strike and the pipe laying gob area. Numerical simulation and theoretical calculation inferred that the coal wall plastic zone width of 3215 mechanized caving face is 8.2m, with the roof caving zone height of 12.5m, the fissure zone height of 45m and the gob area “O” rings horizontal width of 26m. Field practice shows that face gas pumping rate attained 45% to 52%, and the methane concentration at upper corner and return airway stabled 0.8% or less, which illustrated that the application of comprehensive gas control techniques on mechanized caving face effected obviously.