Abstract: For horizontal wells in oil reservoirs with edge water or bottom water, the heel and toe effect and the heterogeneity of horizontal section can lead to a rapid increase of water content. Through the analysis of oil/water properties and flow adjustment and water control screen pipe techniques, and a consideration of the features of laminar flow and turbulent flow, an "active" autonomous inflow control device (AICD) was developed which could automatically adjust additional resistance depending on fluids produced. The hydrodynamics flow field simulation and lab test showed low friction of oil and high friction of water when oil and water flow through the AICD, with the maximum water-oil pressure drop ratio up to 20 or more. Thus, the additional resistance of oil and water was adjusted automatically. A field test of AICD was conducted in Well A, while a horizontal well in oil reservoir with bottom water, Tahe Oilfield. Compared with adjacent wells with no AICD applied, the oil production period of Well A with low water content was postponed for 3 months or longer. The study and test revealed that the AICD could throttle the water produced automatically depending on the fluids produced, so as to avoid bottom water coning in oil reservoirs with edge water or bottom water.