Abstract: In the research on formation of oil and gas reservoirs, especially for the stratigraphic unconformity reservoirs, one of the key problems is quantificational identification of the unconformity structures which should not be ignored. It is very difficult to solve this problem in the buried areas of rift basins because of limitation in research in this aspect at present time. The present paper studied the developing characteristics of unconformity structures in the Eogene period of Jiyang Depression, subdivided the unconformity structures into three types (typeⅠ1, typeⅠ2 and type Ⅱ). These types can be quantificationally identified by core sample testing in the laboratory. As each structure layer of unconformity has an echo in logging data, this paper established a synthetic delamination curve on the basis of selected well logging data and confirmed the location of unconformity surface in the curve by using optimum partition. Using the GR, AC and SP well logging curves, two principle components (PC1 and PC2) curves were constructed. Furthermore, combining the calculated results of PC1 and PC2 with the information of geological research and characteristics of tested core samples, a standard plate of principle components for quantificational identification of unconformity structure types was set up. The above-mentioned method has a good effect on the exploration of stratigraphic oil and gas reservoirs in the Jiyang Depression.