Abstract: In order to solve the problems of mining under pressure of floor sandstone confined water existing at 42201 working face of Buertai Coal Mine, this paper analyzes the hydrogeology condition of 42201 working face based on the data of exploration drilling and effluent of poor sealing holes at upper 22201 working face in the process of mining. And the threatening degree of mining under pressure is evaluated through the calculation data including damage depth of destroyed floor, thickness of effective protection layer, water-resisting ability and water burst coefficient. The direct current prospecting technique is used to detect abnormal vertical and plane distribution scope, characteristics of the watery of floor sandstone aquifer, and drilling verification and draining depressurization are carried out in key water enrichment anomaly area. We also evaluated the sealing quality and predicted the permeable capacity of poor sealing holes of working face, and carried out draining depressurization and grouting measures to seal the area of poor sealing holes for floor sandstone confined water. Finally, the measures of grouting and draining depressurization have good effect though the inspection holes, and safety mining of 42201 coal face can be realized.