A new way to recover the erosion thickness of polycycle basin accurately is introduced in this article，taking Kongdian formation of Jiyang depression in Bohai Bay Basin as an example. The Ek during paleogene period was denuded differently. As is lack of well data in deep zone，it is quite difficult to identify the stratas only by using seismic data. And the erosion thickness of Ek can not be recovered precisely by common methods. So a method based on structural evolution for recovering erosion thickness has been proposed. Divide areas of erosion by using structural evolution sections. Then based on part well data in main erosion area，the erosion amounts of local layers are calculated by means of the sedimentary rate，wave analysis and stratigraphic contrast methods. The result shows that：this method is more accurate than others，which can be used to recover the erosion thickness of the polycycle basin.