Sub lacustrine fan on the background of fault slope development in the lowstand system tract of the third member of the Shahejie Formation, Laizhouwan sag. It has a clear seismic reflection geometric appearance, but the internal structure of the sub lacustrine fan is chaotic, the vertical stacking relationship and plane enrichment position of the sand body were difficult to predict in the exploration and early evaluation stages. Based on drilling,logging,laboratory date,and three-dimensional seismic data, the principles of rheological properties and fluid concentration classification of gravity flow channels in sub lacustrine fan were applied, the sedimentary transport forms of gravity flow were divided into sliding, collapse, debris flow and turbidity flow. Based on the seismic reflection characteristics of channel sand bodies with different genetic transport mechanisms, five sedimentary structural units were identified and characterized in different facies zones of the sub lacustrine fan,they were stacked channels, composite channels, channel wings, single channels, and inter-channels,in addition, the reliability of different unit classification and the differences in sand content through model forward modeling was verifiem. The results indicate that the superimposed channel of the inner fan has developed multi-stage sliding collapse sedimentation, and the overall thickness of the reservoir is large. The composite channel in the lower part of the middle fan has developed sandy debris flow reservoirs with good physical properties, both of which are favorable locations for oil and gas exploration and drilling. The development level of the outer fan reservoir is relatively low. The highly constructive braided river delta from the Kendong uplift provides a large amount of sandy foundation for the sub lacustrine fan, and the slope break zone and ancient landforms jointly control the sedimentary transport mechanism, channel direction, and channel type of the sub lacustrine fan. [ABSTRACT FROM AUTHOR]