Abstract: In order to master the roof water disaster-causing mechanism in 31401 working face in Bulianta Mine, underground drain holes, hydrological observation holes and surface holes were drilled, the water flow, water level and the coupling information of the water level-flow of each hole were monitored, these information were then mined and used to analyze the roof permeability, the overburden deformation law and its relation with the water level change of the aquifer, the ratio of water conducting crack to the mining height and the ratio of caving zone to the mining height. The analysis results showed that the primary cracks in the roof aquifer not developed and had weak permeability before mining; the broken deformation of the overburden starta experienced the opening and closing process, the sandy mudstone cemented and expanded while meeting water, and blocked up the water channel, at the same time, there was a necessary relation between the deformation of the overburden strata and the water level drop of the aquifer, the water level drop laged behind the initial time of the periodical weighting; the primary cracks before mining not developed, the ratio of water conducting crack to the mining height was 31.93 to 34.98 after mining, and the ratio of the caving zone to the mining height was 3.88 to 4.48. It is determined that the periodic roof water inrush channel which appeared on the face was the fractured zone after mining.