Water inrush risk forecasting and evaluation of coal roof and floor are the basic issues of water inrush disasters prevention in coalmine field. Based on Fangezhuang coalmine field in Kailuan，water inrush characteristics and the sandstone fracture aquifer thickness of coal seams from No.12 to No.14，water inrush medium conditions(lithology，interlayer distance)，and water inrush structure conditions，are all analyzed from the two aspects of promotion and treatment of water inrush. Correlation and models between water inrush of coal seam floor and geological conditions are established. And also，the controlling mechanism is discussed. It is shown that water source that induces water inrush in this area takes the confined aquifer of sandstone fracture of coal seams from No.12 to No.14 as the main body. The thickness of sandstone fracture aquifer becomes thicker from the shallow to the depth of the mine field；and water abundance enhancement presents linear correlation. Water isolation of coal floor depends on the thickness of aquifuge and its shale percentage content. Limit thickness of floor mudstone has a positive correlation with water pressure；the abilities of mudstone layer¢s resisting water pressure enhance and water isolation becomes better with the increase of mudstone thickness of coal floor. Thus，the mudstone layer with intact structure floor has obviously larger ability of resisting water pressure than that of mudstone layer with fracture. Water inrush is closely related to the structures. Maximum water emission of water inrush point has positive correlation with fault density. Water inrush from fault is attributed to destructive effect of fault to coal and rock seams，resulting in the increase of its fracture，porosity and the considerable decrease of the mechanical strength around fault. Also，it is controlled by regional tectonic and modern tectonic stress environment. Those achievements provide theoretical basis for water inrush risk evaluation and forecast of floor of coalmine field No.12 and underground water inrush prevention.
