Abstract: The large-scale coal mining actions make great impact on water resources.The pollution and quantity decrease of water resources resulting from coal mining are analyzed in the paper,taking coal mining area of upper reaches of Yangwu river valley,Shanxi,as an example.The non-treatment mining groundwater is directly drained to surface,which pollutes river water,Quaternary unconfined groundwater and confined groundwater.Decrease of regional and usable water resources quantity are visible.Changes of water resources quantity for two different coal mining periods are contrasted.It is put forward that main reason of water resources quantity decrease resulting from coal mining is change of relationship among surface water,groundwater and precipitation.Decrease of usable water quantity are caused by groundwater flow field change,drainage modulus greater than flow modulus,destroy of aquiclude,water inrush of coal seam bottom and water resources pollution etc.