Abstract: In order to study the wellbore pressure characteristics of horizontal wells in bottom water reservoir,the coupling model between wellbore conduit flow and formation seepage has been established.Firstly,on the basis of wellbore conduit flow theory,frictional and accerlation pressure drops have been taken into consideration,then the pressure loss expression of horizontal wells has been deduced.In accordance with mirror reflection and superposition principle methods,the formation seepage of flow expression into the wellbore has been deduced.Lastly,according to Variable mass flow properties,the coupling model between inflow volume and pressure loss has been established.By the use of numerical method,the arithmetic solution and the pressure distribution can be worked out.The examples results show when bottom water reservoir is adopted in horizontal wells,there exists pressure loss and the closer the heeling position,the bigger pressure loss produced.Influenced by this,the liquid producing section lies on the heeling position of horizontal wells.With the increase of production,the greater the proportion of accerlation pressure loss in wellbore.