Abstract: In order to discuss the dynamic mineralization mechanism of Sn-bearing quartz vein morphology zoning in the Weilasituo Sn-polymetallic deposit, three zonations including the upper joint vein zonation, the fault vein zonation and the lower joint vein zonation are analyzed quantitatively by means of vein thickness fractal, tin grades fractal, tungsten grades fractal and mixed distributions. It is found that the similarities of the thickness, Sn-W fractal dimensions and the mixed distributions of ore grades components in the upper and lower joint-vein zonations indicate that the two may have similar metallogenic mechanism. Compared with the upper and lower joint vein zonations, the thickness and the Sn and W grades of fractal dimensions in the fault vein are both small. The focused flow, lower nucleation rate, superimposed growth of veins and the superposition of mineralization may be the reasons for the higher proportions of thick vein and high-grade ores in the fault vein than that in the two joint vein zonations.