Abstract: M8 structure is located in the eastern part of Maichen Depression. It's very important to analyses the character of this structure in detail for the purpose of guiding the next prospect work and understanding the petroleum geological condition of this depression. This structure is an oil-bearing structure which is controlled by M3 fault. Integrative analysis shows that the source rock is Liushagang formation, petroleum generated and blew out mainly after the Miocene Epoch. The mudstone of E2l2 and sandstone of E₂l₃ form the main association of reservoir and capping bed. Integrative analysis and comparison with the nearby area show that M8 structure was a layered reservoir controlled by fault. Based on this analysis, the reservoir pattern is summarized in this paper.