Abstract: At present, there have been no commercial discoveries in oil and gas in the South Yellow Sea Basin, the degree of oil and gas exploration is generally low, and the basic geological research needs to be deepened, especially in the fine sedimentary research. The Well CSDP-2 in the Laoshan uplift in the central part of the South Yellow Sea Basin was selected for this research, and the Middle Silurian Fentou Formation, a set of mainly sandstone facies with good oil and gas potential and rich in asphalt, was studied in detail, and the rock particle size, lithofacies, sedimentary structure, logging facies, and sedimentary facies were analyzed using the core and logging data; and the oil and gas geological significance of different sedimentary microfacies of the Fentou Formation sandstone were explored. Results show that 8 lithofacies types, 6 sedimentary structures and 6 logging facies were recognized. The Fentou Formation mainly developed wave-controlled coastal facies, tidal-controlled coastal facies and tidal delta facies. Correspondingly, four subfacies, including foreshore, delta front, intertidal zone, and subtidal zone, and seven microfacies, i.e., coastal sand bar, return channel, mud flat, sand flat, mixed flat, subtidal sand bar, and underwater distributary channel, were deciphered. In addition, through the statistics of the porosity of the sandstone sedimentary microfacies of the Futou Formation, including filling asphalt, the reservoir physical properties of the hydrocarbon accumulation period were revealed. The asphalt in sand flat and subtidal sand bar reservoirs in the tide-controlled coastal environment were developed and the surface porosity is high, reflecting good physical properties of the reservoir in hydrocarbon accumulation period. In the tidal shore environment, the asphalt contents of the deltaic underwater distributary channel and the coastal sand bar reservoir in mixed flat, return channel, and wave-controlled shore environment were relatively low, followed by the surface ratio of porosity, and the reservoir properties remain relatively poorly studied. This study provided a good reference for the oil and gas exploration in the Paleozoic sandstone in the South Yellow Sea, and a good geological basis for further oil and gas exploration in the South Yellow Sea Basin.