Abstract: Oil reservoir in 5 wellblock of Bohai S oilfield is characterized by big thickness, high viscosity and narrow strip distribution on the plane. Based on fine geological models, by using of reservoir numerical simulation method, the reasonable oil producing rate for the edge and bottom water reservoir developed with horizontal wells has been studied. Meanwhile, the variation regularity of water cut, daily oil production and recovery degree under different production pressures has been analyzed. As offshore oilfield production is mainly constrained by the platform life span, the reasonable production pressure should be determined, and then the new understandings for effectively developing edge and bottom water reservoir with horizontal wells can be provided, which is centered on geological reservoirs and taken offshore conditions into consideration and of strong theoretical and practical uses.