The Shapinggou molybdenum deposit is the second largest porphyry molybdenum deposit in the world. The mafic-ultramafic rock widely exposed in the area of Shapinggou molybdenum ore deposit is an important medium to reveal the deep information of the deposit. In this paper, the olivine-bearing amphibolite outcropped in the mining area were studied based on petrology, petrography and in situ analysis so as to clarify physicochemical conditions of diagenesis and discuss the petrogenesis and tectonic setting. The main rock-forming minerals contain olivine, amphibole, phlogopite and pyroxene, and the accessory minerals are apatite, chromium-iron spinel, mafic spinel, magnetite, pyrrhotite and pentlandite. The results of in-situ analysis of EPMA show that olivine belongs to the chrysolite series, amphibole is parasite, pyroxene is diopside and mica is phlogopite. The order of crystallization is olivine-pyroxene-amphibole, the temperature ranges from 1 111.64 to 1 223.30℃ and the formation pressure ranges from 350 to 740 MPa, with high oxygen fugacity (the oxygen fugacity varies from NNO+0.59 to NNO+2.27). The mineralogical characteristics of phlogopite and amphibole indicate that phlogopite was related to mantle-derived magmatism. The study shows that the parent magma of olivine-bearing amphibolite originated from the mantle and was formed through crystallization differentiation of basalt magma which was partially melted by 7.92% of the mantle. The olivine-bearing amphibolite outcropped in the north of Shapinggou mining area should be the product of partial melting of mantle-derived magma under the extensional tectonic background.