Abstract: The 2nd member of Shahejie formation is an important oil bearing series of the area with abundant Gastropoda fossils which provide an effective means to reconstruct the paleogeographic landscape of their habitat. Characteristics and distribution of their assemblage are reviewed, with particular emphasis on the occurrence, evolution and environment of the predominant genus Tulotomoides. The changes of surface relief of the 2nd member of Shahejie formation as shown in the section indicate the contraction of the lake basin from east toward the west, which caused the eventual disappearance of the Dongying Lake with the encroachment of the alluvial plain.