Based on Wutongzhuang Mine integrated hydrogeological exploration data before and after the initial mining surface mining, hydrological dynamic observation data before and after the inrush and the characteristics of water inrush, etc., the cause of first mining face inrush was analyzed and demonstrated. It was concluded that under the condition of natural B1, B3 hole of top-down vertical line within the scope of strata or high angle fracture density was inrush internal cause and control factors, mining influence was the main factor that prompted the hydrogeological conditions changing, ordovician limestone supply wiled green water-bearing stratum water supply increased, wiled green water-bearing stratum water level rose, promoted the cause of floor water inrush, ordovician limestone water-bearing stratum water enriched zone and high water head were water inrush source material and dynamic conditions.