The Laoyemiao Oil Field is geographically located at the Laoyemiao Village，Tanghai County，Hebei Province，and tectonically located in the northwest of the Nanpu Sag in the Bohai Bay BasinIt is one of the important oil fields in Ji Dong Oil FieldsThis paper analysed sedimentary characteristics such as rock composition and its texture，color of shale，sedimentary structure and lithofacies combinations，as well as the  palaeotopography and palaeogeography of the Oil FieldIt was shown that the Member 1 of Dongying Formation of Paleogene in the Laoyemiao Oil Field was formed in a fandelta environmentMain microfacies including the fandelta subaqueous distributary channel and mouth bar were divided，and the characteristics of each microfacies were analyzed as wellSedimentary facies map of the Member 1 of Dongying Formation in the Laoyemiao Oil Field was plotted with logging facies and isopachs of sandstone，and the evolution process of the microfacies was further analyzedAccording to microfacies map and core analysis data,subaqueous distributary channel was believed to be the main reservoir microfacies，whose porosity is 15%～24% and permeability is 150×10-3～500×10-3μm2For the Dongying Formation reservoir in the Laoyemiao Oil Field，the distribution scope of subaqueous distributary channel，low reservoir sorting and strong heterogeneity are the main geological factors for low development effect And as a result，excellent reservoir can be forecasted by reconstructing microfacies and oil field development plan can be adjusted accordingly