This paper reports the geochemical characteristics of platinum-group elements (PGEs) in nephelinite lavas from Wajilitag complexes of Bachu County in Xinjiang. The magma source and the magma evolution of nephelinite are discussed. The values of such platinum-group elements as Os, Ir, Ru, Rh, Pt and Pd in nephelinite were determined by ICP-MS. They display a positive slope in the mantle-normalized pattern. The fact that Pd/Ir values are higher than those of the primitive mantle suggests the fractionation of PGE in nephelinite. And positive correlations for PGE versus MgO, negative correlations for Pd/Ir and Cu/Pd versus MgO suggest that the PGE differentiation was probably controlled by crystallization differentiation of olivine. It is also one of the factors that cause the high Cu/Pd ratio and magma S saturation. The Cu/Pd ratio indicates that the magma is sulfur saturated magma, but there is no factor that leads to the S-oversaturation of magma and sulfide liquation. Sulfur capacity calculation shows that, compared with other rocks of large igneous province, Wajilitag nephelinite is extremely depleted in PGE due to the S-oversaturation of parent magma, with the main reason being the low degree partial melting of the mantle. It is considered that the partial melting degree of mantle source played an important role in the formation of Cu-Ni sulfide PGE deposits in the Tarim Large Igneous Province.