TO investigate the water-inrush process due to floor heave，simulation mode1 was made and factors of mining height，immediate roof strength，water pressure，depth and strength of confiningbed，excavation step distance and bury depth were analyzed by using UDEC software．Five zones theory(containing two maximum main stress circles and three maximum main stress stratiform zones)along excavation direction was proposed， and two ends-fixed beam mechanical model in maximum main stress circle was established．It is found that water inrush always occurs at the end of the beam where shear stress is higher, that is to say it always occurs at near the starting cut and working face。 Water pressure，height and strength of confiningbed are the determined factors，and mining height，immediate roof strength。excavation step distance and bury depth effect water inrush process due to floor heave．