Abstract: Xiayukou coal mine is threatened by ordovician water from coal floor when mining 11# coal seam,thus?it is necessary to carry out the feasibility study before the mining under water pressure.By analyzing the aquifer,aquiclude and the water filling sources and passageway of Xiayukou coal mine,the water inrush risk of 11# coal seam is evaluated with water bursting coefficient.The results show that the aquiclude in the floor of 11# coal seam has good water-proof capability with stable thickness and dense lithology;the coal seam floor water burst coefficient of No.11 coal seam is only a small part area less than 0.06,most of the areas in the field have a water inrush coefficient of more than 0.06and a very dangerous area greater than 0.1,the action of mining need to be carefully.The results provide theoretical guidance for the exploitation of the Xiayukou coal mine, which is conducive to the safe and efficient production.