Abstract: Damoguaihe Formation of Bei'er Depression, an Upper Jurassic lacustrine sequence up to 2000 m thick, mainly consisting of subaqueous fan and offshore to shoreline deposits. The lower sequence of Damoguai he Formation typically consists of debrisdominated subaqueous fan deposits which can be divided into three subfacies and then seven microfacies. Middle sequence formed during episode of high lake level, with offshore bars along the subdued margins of deeper water. The Upper sequence of Damoguai he Formation results from the contraction of the lake system, and mainly coinsisted of beach and bar deposits. Analysis of Damoguai he sandstones shows that the volcahiclastic lithic sandstones were derived from magmatic arcf. Porosity reduction with depth of burial was controlled largely by co^npaction during diagenesis. Early diagenetic processes increased porosity in the shallow volcaniclastic sandstones, Which took place earlier then the hydrocarbon generation in space. Based on diagenetic events related to temperature, Damoguai he Formation can be divided into shallow, intermediate, and deep diagenetic zones.