Abstract: Abstract: Lacustrine deltaic and lacustrine deposits are a major type of sedimentary facies of the Upper Jurassic Penglaizhen Formation in the Baimamiao gas field. There are usually 2-3 distributary channels entering the study area from the northwest. This delta belongs to a river-dominated birdfoot delta. Lakeshore and shallow Lake deposits are main microfacies types of lake facies. In the study area, the delta front is a dominant microfacies, and sandbody distribution is apparently controlled by underwater distributary channel, river mouth bar and distal sandbar microfacies. Finger sandbars and compound sandbars are favorable reservoirs of Members III and IV (principal gas-producing zones) of the Penglaizhen Formation. The intensive study of sandbody distribution based on the sedimentary microfacies study will be always one of the important subjects of the geological study of the Baimamiao gas field in the future.