Abstract: In order to improve the gas drainage efficiency of the mining crack zone in the fully- mechanized top coal caving mining face in No.3 Seam of Wangpo Min e,a high location of the crack zone was accurately found. Based on No. 3215 fully- mechanized top coal caving mining face of Wangpo Mine as the engineering backgroun d,a numerical calculation method and " double end water sealing method" were applied to the analysis and site measured Analysis on the crack height of the overburden st rata above No. 3215 fully- mechanized top coal caving mining face of Wangpo Mine. The Analysis results showed a good consistency. The Analysis showed that the crack h eight of the overburden strata above No. 3215 fully- mechanized top coal caving mining face was 54 ~ 57 m and the numerical value and the site measured results could a ctually reveal the crack height condition of the overburden strata above the coal mining face. The study verified the feasibility of the " double end water sealing method" to measure the crack location in the underground mine and could provide technical solution to optimize the high level borehole stratum in the mine as well as the mine with th e similar conditions.