Abstract: In this paper, the petrographical characteristics and mechanical properties of Zhejiang granite are studied to elucidate the relationships between them. Close scrutiny of the mineralogy and mechanical properties of the granite provides a good signs of metasomatic alteration in these rocks. Engineering properties of rock material, which depend on the physical properties, can be predicated when the relevant parameters are defined quantitatively. Microscopical observation, hardness, density, porosity and point load strength values can be used as quantititative indicies of studied granite, and each of these factors gives a reliable indication of the engineering case of the rock. The engineering properties and mechanical behavior are functions of the physical properties of the rock constituents and controlled by the alteration state.