The Tongshan skarn type copper deposit in Guichi county has well-developed garnet skarn zone. Garnets in this area can be classified into three types, i. e., andradite, grossularite and andradite-grossularite, of which the last type is most commonly seen. The massive garnets are isotropic, while subhedraleuhedral garnets are anisotropic with well-developed zonal structure. According to the calculation of isomorphic end molecule percentage of garnets, the zoned garnets have three variation types in their molecule components. Studies show that the zonation and nonhomogeneity of garnets are related not only to their isomorphic molecule percentage, but to their formation environment as well.