Abstract: In order to solve the gas content over limit problems in No.21141 Coal Mining Face of Zhujiao Mine, according to the less borehole engineering, high gas emission, low gas drainage rate and other problems existed in the mining seam drainage operation, the paper analyzed the main sources of the gas emission.The gas d rainage technology with different gas sources was applied.While the borehole drilling in and along the mining seam continuously conducted, the borehole sealing techni que in the mining seam was improved with YFF-9 pneumatic borehole sealer.Also the high level borehole gas drainage technology was applied.The results showed that after the gas drainage operation conducted with different sources, the net value of the gas drainage in the coal mining face generally would be over 7.8 m3/min, the gas volume fraction in the air return flow would be reduced to about 0.4%, the gas volume fraction in the top corner would be reduced to 0.4%0 .9%，the number of the gas C ontent over the limits would be obviously reduced and the gas drainage rate of the coal mining face reached to 62.3%.Therefore, the gas content over the limit problem of the coal mining face was solved.