Abstract: According to the gas occurrence characteristics in high gas and low permeability coal seam, combining with the gas emission laws at fully mechanized caving face and taking 103 fully-mechanized caving face (“U + I”) in Shiquan Coal Mine in Huadian Coal Industry Corporation as an example, fluent software is used to simulate the gas emission at working face and the gas control effect by internal interlocked tail road at fullｙ-mechanized caving face is analyzed. The research shows that internal interlocked tail road is the important supplement of gas extraction and plays a good role in controlling gas at fullｙ-mechanized caving face. When the returning air volume of internal interlocked tail road is one-third of the total air volume of working face and the concentration of return current in internal interlocked tail road is from 1% to 2%, the gas concentration does not exceed in return current and the upper corner at working face. The gas concentration in internal interlocked tail road is linear correlation with the gas concentration change in return current and upper corner, and the stability of gas drainage in tail road is the important guarantee to solve the problem of gas in the process of mining at fullｙ-mechanized caving face.