The distribution and weathering characteristics of granite in the western coastal site of Guangdong province are described. A series of in-situ tests are conducted

including the velocity tests

load tests and in-situ shear tests

along with laboratory tests involving conventional compression test and consolidation test. Based on test results

the physico-mechanical properties of highly weathered granite are analyzed. It is indicated that: (1) Due to strong physicochemical weathering processes，the unstable elements in bedrock are leached which further result in formation of aluminum-rich-and iron-rich types of thick weathering crust. Heterogeneity of rock is obvious. (2) Natural moisture content and void ratio of highly weathered rockmass vary greatly

while natural density and modulus of compression change moderately. (3) Particle sizes have a great impact on the physical characteristics of weathering granite. The physical indexes are stronger as the decrease of particle sizes. (4) Wave velocity is closely related to the weathering degree and particle composition. (5) Water content has more apparent effect on cohesion than friction angle. The attenuated effect on cohesion of highly weathered granite is obvious in particular. The research results can provide basic data for construction of nuclear power station and optimal design.