Abstract: Water-inrush from roof is one of the most harmful hazards to coal mine construction and production. The technologies of slanted drilling and drainage have been widely used in the field of coal mine water prevention and treatment, especially in preventing and controlling the water-inrush from roof. Based on the theory of point source space,this paper derived a calculation method of the well flow caused by slanted borehole in infinite horizon confined aquifer. Superposition of infinite horizontal porous confined aquifer complete slanted bore-hole flow calculation equa- tion has been verified. A set of analysis,simulation and forecast of the coal mine roof slanted borehole drainage theory and method of water was formed. Calculation equation for slanted borehole laid a good foundation to the design of the coal mining face water discharge.