Abstract：In order to analyze sedimentary environment and change law of water deepth in the middle part of third member of the Paleogene Shahejie Formation in Wenliu area, Dongpu Sag, the research method of ichnology and sedimentology is used, through the observation of drilling cores and identification of trace fossils, 11 ichnogenus and 16 ichnospecies are discovered in the study member. These ichnofossils can be divided into4 ecological types: Palaeophycus-Planolites ichnoassemblage, appeared in the Shallow lake and fan delta front environment; Planolite-Mermoides ichnoassemblage is formed in the Shallow lake and semi deep lake environment;Helminthopsis-paleodictyon ichnoassemblage occurred in the front fan delta environment;HelminthopsisTrichichnus ichnoassemblage generated in the turbidity fan environment. The research results not only provide the evidences on palaeoenvironments and palaeobathymetric analysis but also offer new factor formation to predict oil and gas deposits in Dongpu Sag.

Keyword：Dongpu Sag;Shahejie Formation;trace fossil;Ichnoassemblage;sedimentary enviroment;