Lailishan tin deposit is located in the Tengchong-Lianghe tin metallogenic subzone of West Yunnan tin metallogenic zone, and is between Nujiang suture zone and Myitkyina suture zone in Tengchong block south of Sanjiang tectonic zone. Tin ore body occurs in the Middle Carboniferous SIGUANGPING group fracture with granite contact zone and the Lailishan complex Southeast edge,Tin Mineralization was closely related to the syenite granitic magmatic activity. The syenite granite has SiO2 content of 76.00%~77.10%, Al2O3 content of 12.62%～13.50%,TFeO/MgO of 9.79～72.50, With rich silicon and aluminum, higher Iron、lower magnesium;A/CNK of 1.02-1.32, K2O/Na2O of 1.42-2.26, and Rittman index（δ） of 1.40-2.29, and thus belongs to the high-K calc-alkaline and peraluminous granite series. Rock ΣREE = 98.68×10-6~191.89×10-6, A strong negative Eu anomalies (δEu=0.07-0.10), no clear Ce anomalies (δCe= 0.63-0.99); LR/HR=0.19-0.69, (La/Yb)N=0.31-1.24; no clear differentiation in light and heavy rare earth elements; severe depletion of P and Ti, depletion of Ba, K and Nb, enrichment of La, Zr, and Th. These results indicate its type is shellsource S-type syn-collisional granite. Its age was determined by LA-MC-ICP-MS U-Pb method to be (52.53 ±0.29) Ma (MSWD=1.8), and it resulted from Middle Eocene India-Eurasia collisional orogeny, In the strong crustal extrusion、thickening、formed by the upper crustal shale rocks in the unsaturated water under the conditions of low degree partial melting magma emplacement condensation. Metallogenic material there originated from surrounding rock and granite, and Metallogenic fluids were mainly composed of magmatic water. The age of Metallogenic was consistent with the diagenetic age of syenite granite. Tin ore reflects the response to the magmatic activities during Early Himalayan India-Eurasia collisional orogeny, and indicates that 51.1Ma-54Ma ago in this area, there was at least one tin metallogenesis closely related to the syenite granite in Lailishan.