Abstract: Five water outbursts have occurred in working no.4 of Baodian Coal Mine and the most water yield was up to 285.4 m³/h. According to plentiful montoring data of the quantity,quality and level of watet,the authors resch a conclusion that ground-water in red beds of Upper Jurassic System is source of water inrush,fissures induced by mining is passageway of water inrush, and patterns are roof leakage and water outburst after mining. Groundwater in red beds exists a relative good hydraulic connection and drawdown ratio of piezometric level increases with extending of extent of fissures induced by mining, this shows that water inrush of working no.4 withdraws the static reserve of groundwater in red beds.