Geochemical characteristics of the volcanic rocks in middle Wusunshan of West Tianshan Mountains were studied in this paper, and the results show that all the basalts and andesites are tholeiitic volcanic rocks, with enrichment of LREE [(La/Yb)_N=3.44～11.36] and weak depletion of Eu (δEu= 0.79～1.13); andesite and rhyolite are significantly enriched in highly incompatible elements (Cs, Rb, Ba, Th, U) and LREE; basalt and acid rock samples show slight difference, but all the samples obviously have negative anomalies of Nb, Ta and Ti. Nevertheless, the characteristics of basalts are similar to those of intraplate basalt: the (Th/Nb)_N range from 2.02 to 8.12, (Nb/La)_N range from 0.40 to 0.45, by far less than 1; La/Ba ratios are low (0.01 to 0.07) and Ba/Nb ratios are high (90 to 410); average Zr/Nb ratio is 16.48, close to the ratio of primitive mantle (15.71 ); Ta/Nb, Hf/Ta, Th/Yb ratios are averagely 0.10, 3.77, 0.64 respectively, close to their upper crust ratios (0.10, 3.50, 0.48); Zr content is larger than 90×10^-6, Zr/Y ratios are about 4; Except for some active elements (Cs, Rb, Ba), values of trace elements are close to their values in the lower crust. Combined with the geological characteristics of this area, the authors consider that this region might have been in the post-collision extension phase in the Carboniferous, with local rifting characteristics. The distinct depletion of Nb,Ta and Ti might have been caused by the hybridization of the lithosphere, and the environment of the Middle Wusunshan volcanic rocks should have belonged to the post-collision extension phase.