Abstract: In order to provide the data support for the resolution of the upper corner gas accumulation problems in the fully mechanized top coal caving mining face in the high gassy low permeability and difficult drainage seam, the controlled single element method was applied to the layout of the cubic mesh type measuring points. The measurement and analysis was conducted on the gas density 3D distribution of the coal mining face and the isoline figure of the gas density distribution was draw n.According the data analysis results as well as the gas conservation equation and the air flow conservation equation, the total gas emission quantity in the goaf during the coal mining period was 1.77 m3/min and the gas emission quantity from the coal walls was 2.30 m3/min.The emission quantity of the cut coal was 1 87 m3/min.The total ventilation discharged gas quantity of the coal mining face was 11.88 m3/min.The ratio of the gas emission quantity from the cut coal, coal wall and goaf was 31. 5%, 38.7% and 29.8% individually.