Abstract: With attentive observation and description for the cores from a depression of East China Sea shelf basin, 28 lithofacies types are identified from the cores of Huagang Formation in the study area, including 5 for conglomerate, 15 for sandstone and 8 for fine-grained rock. By the analysis for the cores from 22 wells, 2227 numbers of lithofacies and microfacies data are obtained. Three sedimentary systems, i.e. lakes, deltas and rivers, are developed in this area, dominated by lacustrine sediments. The Markov chain analysis is used to analyze the sequence patterns of lithofacies in different sedimentary microfacies and establish the possible lithofacies assemblages and quantitative lithofacies assemblage probability. The results will provide a geological database for further study of the same or similar types of sedimentary facies and a quantitative basis for the identification of sedimentary facies.