Abstract: Numerical simulation and on-site test were combined to research the coal mining technology of Y-type ventilation with thick and soft coal seam systematically for the problems of deep buried coal seam group, soft coal quality, high gas pressure and gas content in the coal seam of the eastern part of China. Evolution characteristics of surrounding rock cracks in thick coal seam mining and the vertical displacement and subsidence were obtained in this paper. The research result showed that the bed-separated fissures and lengthways fissures of overburden rock stratum in the location of 10 times mining level were most developed. Gas enrichment zone and crack network which can provide a passage for gas drainage were formed here. The method of gas drainage in large diameter drilling group was designed, and the pressure-released gas in roof fractured zone and the gas in gob were effectively controlled by large diameter borehole and pipe-buried technology. Finally, the gas concentration in the air was controlled below 0.3%, and efficient gas drainage was realized by the method that high dip high drainage roadway gas was replaced by large diameter borehole.