Abstract: For oilfields which have already came into high water cut stage,potential layers and high water cut layers coexist vertically because of serious heterogeneity.It is easy for water breakthrough while fracturing because the interbed is generally thin.Therefore,the estimation of barrier function for interbeds and fracture height controlling are very important for hydraulic fracturing,which are also the difficulty and critical points of fracturing optimization design and well selecting.Based on the qualitative research on the barrier function of thin interbed,experiments were conducted on the interbed limits,and a new method of fracturing interbed selecting has been put forward.At the same time,the corresponding technics is provided,and 27 wells have been tested on-site.The conventional viewpoint that fracturing couldn’t be conducted if the interbed is less 4 m is broken.This technology enlarges the range of selecting wells and layers for fracturing and has very important significance for improving the reservoir stimulation efficiency in high water cut stage.