With one year data of 52 permanent stations and 11 new temporary stations,we obtained Rayleigh surface wave phase velocity distribution images of cycle 10～50s in Xinjiang Tien Shan and its surrounding areas(41°～48°N,79°～91°E) by ambient noise tomography method. The S wave velocity structure of the earth's crust and upper mantle in the study area is also obtained by using MCMC method based on Bayesian. The results show that the sedimentary cover in Junggar Basin is deep in the south and shallow in the north,and the thickest part can reach nearly 15km. In the vicinity of the basin-mountain junction in the northern and southern parts of the Tien Shan orogenic belt,there exist some clear low-speed zones in the crust that is inclined toward the orogenic belt. Combining previous research results,we speculated the subduction of Tarim Basin and Junggar Basin to Tien Shan orogenic belt mainly in central Tien Shan orogenic belt in China,and eastern and western Tien Shan are only one-way weak subduction. There are obvious low-velocity anomalies in the lower crust of the Tien Shan orogenic belt,which reflect that the medium has low mechanical strength and is more prone to deformation and uplift under the extrusion environment. The low-velocity anomalies in the lower crust may be closely related to the existence of the ancient plate suture belt,and the bidirectional subduction of the continental masses on the north and south sides of the Tien Shan and the extrusion deformation.