The Bastielieke deposit is a W polymetallic skarn deposit discovered in the South Altay, Northwest China. W polymetallic mineralization mainly occurs within the contact zone between the Permian intrusions and the Kangbutiebao Formation (Fm.) metamorphic volcanic-sedimentary rocks. Permian granitoids associated with W (Cu) mineralization include several phases of granite: biotite granite (G1), monzogranite (G2) and two-mica monzogranite (G3) in L2 ore block, biotite monzogranite (G4) in L3 ore block. We obtained zircon U-Pb ages of G3, G4, and barren porphyritic monzogranite (G5) from Lamazhao granite of 275.0 Ma, 275.4 Ma, and 277.0 Ma, respectively. All samples from G3, G4, G5 show enrichment of SiO₂, weakly peraluminous, enriched in light rare earth elements (LREE), and depleted in high field strength elements (HFSE). These Permian granitoids were mainly derived from mantle magma, and mixed with some lower crust components, although the Sr-Nb-Hf characteristics are slightly differences. G1, G2, and G4 were involvement of more mantle components than G3 and G5. G1 and G5 have experienced more obviously fractional crystallization than G2, G3, and G4, and G5 displays the highest fractionated degree. Moreover, G5 has the highest magmatic oxygen fugacity compared with G1, G2, G,3 and G4 according to variable △FMQ values (G1: −2.75 to 1.42, G2: −3.14 to 2.23, G3: −3.15 to 0.70, G4: −2.92 to 1.36, and G5: −1.63 to 2.82, respectively), as well as δEu values, δCe values, and Ce/Nd ratios. Thus, we proposed that tungsten skarn mineralization in the Bastielieke deposit area is mainly controlled by high fractional crystallization, and the contribution of magma source and oxidation state cannot be neglected. In addition, the copper could be offered by oxidized fluids exsolved from mafic magmas or Cu-bearing immiscible magmatic sulfides in copper-rich tungsten skarn system.