Abstract: Based on seismic, drilling, core and well logging data, through comprehensive analysis of lithofacies,particle sizes, mineral maturity and seismic facies, Taizhou uplift was made clear to be the main provenance orientation of the first member of Dainan formation in Qintong sag and the first member of Dainan formation is provided with the material source, topography and dynamic conditions for forming a ring concave fan body.Combined with the lithofacies, seismic facies analysis and reservoir wave impedance inversion, two nearshore subaqueous fans were developed in the area around western Qingtong sag. The exploration degree of the area around western Qingtong sag is low and the remaining resources is large. The discovery of the ring concave fan body in the first member of Dainan formation not only changes the previous understanding of undeveloped reservoir in the west, but also makes clear three favorable exploration zones, namely steep slope zone, deep concave zone and inner slope zone. Besides that, the exploration targets, the structure-lithology and lithology reservoirs are also made clear, which points out the exploration direction in the next step.