Abstract: A analysis about the conditions of water inrush form mining floor and its site are based of forecasting water inrush.Based on the developing law of supporting pressure and the distributive characteristics of floor stress,this paper analyses the conditions of water inrush from mining floor and its site.The conditions of water inrush are as follows,the floor is broke by mining pressure,with the result that valid thickness of aquifuge is reduced to zero,and water pressure is not less than side pressure in unload area.Before inside and outside stress is formed,the site of water inrush is situated on the waste.After inside and outside stress is formed,that is situated closed to the wall.