Abstract: Shuanghe Oilfield has already came into high water cut stage, serious Heterogeneity, inter-exists of potential zone and strong flooded portion in vertical, thin interbed, and easy breakthrough of water, all these problems cause it difficult to selection wells and layers during fracturing. Based on qualitative research of thin interbed barrier in situ-geological condition, combined with field data, we studied the minimum interbed thickness in controlling excessive extend of fracture, and educed that:at 4 m3/min displacement, the minimum thickness of barrier of puremud interbed is 3.0 m, and figures have been drawn out to select interbed thickness. Our research has extended ranges of selecting wells and layers during fracturing, which is very useful for the reconstruction of old oilfield.