Abstract: in oderto solve the foor water inush problem caused by the requent and serious site roof pressuized.according to the meaured mine pressure behavior features of the coal mining face with the deep depth and thin base ock,the colapsing and instaility distinguishing metned of the key layer was applied to analaze te bumping load role mechanismn when the roof was pressurized.The elastic theary and Mohr-Coulomb crieion were applied to derve the calculation formula of the fcor faiure depth in the coal mining face under the roof bumping load and suppor prssure superpostion role and to stucy the eationship betwee the roo ressuized and foor falure depth. The related control technology of the foor fallre depth was provded and the production eficiency was improved by 91.7%. The results showed he longer steap distance of the prof ressuized.the higher bumping load woud be. The superpoition role of the roof bunmping load and supot pressue would causethe foor falture depth increased.with the step distance of the roof pressurized inreased,the foor faltre depth waould be increased frt y and then woul be in stabe.The periodicity of the roof serious pressurized would cause the periodicity of the floor failure and floor water inflow.