Abstract: Interbed is an important parameter to characterize reservoir heterogeneity.It is also the keyfactor influencing residual oil distribution.Based on core,logging and geological statistic data,the ori-gin,distribution and influence on residual oil of interbed in braided channel sand bar of braided channeldelta of the Triassic lower oil group in the Tahe Oil Field were studied.The interbeds were divided intomuddy,calcareous and petrophysical ones.They might distribute contiguously,or in lens shape con-trolled by single well,or sometimes deposit due to irregular erosion and filling.The upper interbeds inreservoir have the strongest control on residual oil.The muddy interbeds near to oil-water interface atthe bottom have less control on residual oil.The middle ones have the least control.