Abstract: The present paper deals with the application of the vitrinite reflectance trend method to the restoration of erosional thickness of the Dongying Formation in the Nanpu depression. The prerequisite for this method is the selection of suitable Ro data for a single well. Otherwise, the Ro data for different wells in the same burial history and same tectonic unit may also be available as well. The results of research in this study result in the construction of the contour diagram for the erosional thickness in the Dongying Formation. The erosional strength may be discriminated into two parts:relatively strong in the northeastern part and weak in the central part of the Nanpu depression.