With the exploration difficulty increasing, the fine exploration becomes more and more important to the oilfields, especially the eastern old oilfields in China. The authors analyzed the method of the fine exploration in the old oilfields based on the research of Putaohua Formation in Xujiaweizi area, Songliao Basin, divided the targets in vertical direction, and carried out sedimentary microfacies study to make clear the distribution of the target reservoir by using seismic reservoir inversion and logging facies analysis. By overlapping 3D fine structural map and reservoir distribution map, the targets were synthetically analyzed according to the lithologic reservoirs exploration method, which proved a good exploration effect.