This paper reports the characteristics of the Beizhan phlogopite pyroxene peridotite pluton and diorite veins from West Tianshan, Xinjiang. Laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) U-Pb zircon dating of the Beizhan phlogopite pyroxene peridotite yielded an age of 302.5±1.3 Ma, and phlogopites from phlogopite pyroxene peridotite yielded a well-defined ⁴⁰Ar/³⁹Ar plateau age of 298.1±1.9 Ma, which show excellent agreement with the mineralization age of the Beizhan iron deposit. Beizhan phlogolite pyroxene peridotite exhibits relatively lower SiO₂ (42.51%~50.82%),Al₂O₃ (4.87%~7.38%),TiO₂ (0.25%~0.77%), Na₂O+K₂O (0.87%~1.87%),and higher MgO (26.36%~30.17%), TFeO (12.33%~15.99%) content. The high Cr (523×10^-6~7 026×10^-6), Ni (906×10^-6~1 088×10^-6), Co (109×10^-6~132×10^-6) and Mg^#(0.76~0.79)values of the Beizhan phlogolite pyroxene peridotite suggest that olivine accumulation occurred in the magma. The calculation based on the highest Fo of olivine from phlogolite pyroxene peridotite and the TFeO content of the whole rocks suggest that its parent magma is basaltic affinity. All the rocks display LREE-enriched and flat HREE patterns,and show the enrichment of large ion lithophile elements (Rb, Ba, U, K) and the depletion of high field-strength elements (Nb, Ta, Zr, Hf, Ti), as well as the positive Pb anomaly. Phlogopite proxene peridotite has low initial ⁸⁷Sr/⁸⁶Sr ratios of 0.704 4~0.704 7 and high εNd(t) values of 2.23~3.90,and diorite has initial ⁸⁷Sr/⁸⁶Sr ratios of 0.704 4 and εNd(t) values of 3.79~4.07. These homogeneous Sr, Nd isotope compositions suggest that they were derived from the same source region. Furthermore, the trace element signature suggests that phlogolite pyroxene peridotite was derived from a spinel-facies asthenosphere mantle source, which had been modified by subduction-related melts/fluids. Combined with regional tectonic setting, the authors infer that the Beizhan phlogopite pyroxene peridotite was derived from the upwelling of asthenosphere mantle caused by the detachment of the West Tianshan orogenic root zone in Neopaleozoic. It is also suggested that the Beizhan iron deposit was formed under the same geodynamic setting.