Located in the northeastern margin of Tarim Plate,the Pobei mafic-ultramafic intrusion consists of several intrusive bodies, such as Poyi, Posan, Poqi, and Poshi, in which the Poyi and Poshi intrusive bodies show the better metallogenic potential. In the past, the Pobei intrusion was considered to have been geodynamically formed in the post-collisional setting or the mantle plume setting. In this paper, systematic mineralogical and geochemical data of the Poyi intrusive body were used to reveal the geodynamic setting. The results show that the Fo values of the olivine range from 83.17 to 90.2, the orthopyroxene minerals are mainly bronzite, whereas the clinopyroxene minerals are mainly augite and endiopside; the Cr^# and Mg^# of chrome spinel range from 0.45 to 0.69 and from 0.11 to 0.41, respectively, and show the evolution trend from Al and Mg richness to Cr and Fe richness. The trace elements display obvious Nb, Ta, Ti negative anomalies and Pb positive anomalies. The variations of major elements are mainly controlled by fractional crystallization/cumulate action of olivine, pyroxene and plagioclase The MgO content and FeO content of parent magma are estimated to be 16.09% and 10.38%, respectively. The initial crystallization temperature of parent magma is estimated from 1 331℃ to 1 411℃, indicating that the parental magma is picritic magma. The Pobei intrusion might have been derived from a high degree of partial melting of matasomatized lithospheric mantle during the activity of Tarim mantle plume.