Petrology, mineral chemistry and trace element geochemistry of the dunite xenoliths in gabbro-dioritic rocks from western Shandong indicate that the dunite xenoliths would be relicts of high degree partial melting of ancient (Archean) lithospheric mantle. Two types of the mantle metasomatisms occur in the dunite xenoliths, i.e. early CO2-H2O-rich anti-active liquid metasomatism by the representative of interstitial phlogopite and late silica-rich melt (liquid) metasomatism by the representatives of orthopyroxene veins and net orthopyroxene between olivine and chromite. The asthenosphere-derived silica-rich melt (liquid) metasomatism in the upper mantle is a chemical erosion to ancient lithospheric mantle. It is of important significance to realize the nature of Mesozoic lithospheric mantle and mechanism of lithospheric thinning.