In order to accurately differentiate the height of caving zone and fissure zone liyazhuang coal mine, by using UDEC4.0 numerical simulation software for 2-226 working face coal rocks, the two zone height is 11~13 m and 40~44 m, evident vertical fracture cracks appeared in the goaf on both sides of the 20~30 m range; site by comparing the scalar extraction gas of high drilling field to get that:the effect is best of extraction gas of high field drilling hole horizon eventually distance coal seam hanging high of 11~23 m,And a hole location is drilled that optimization result is 14.7 m, the result tallies inspact with the numerical simulation results;The research results provide certain basis for other similar conditions of mine stope and goaf gas control.