Abstract: L oilfield in Zhujiangkou basin is a thick layer of marine sandstone reservoir, because of few wells and undeveloped, coring data are limited, it is difficult to make clear the distribution of thick sand body and reservoir interlayers, while the unstable distribution of interlayers in the reservoir is the most important geological factor affecting the development plan. Through the core observation, thin section identification and logging analysis, based on the understanding of regional geology, compared with the distribution characteristics of interlayers in the developed thick sandstone reservoirs in Zhujiangkou basin, the distribution patterns of interlayers in the study area was summarized. In combination with post stack geological statistics inversion, the quantitative characterization of the interlayers in the study area was made clear. The research results indicate that the interlayers of the study area can be divided into four categories: top calcium,inner calcium, laminar interlayer and physical interlayer. The research results have good guiding significance for the determination of well pattern and well network deployment in the development plan of L oilfield, which can effectively avoid the corresponding geological risk.