Abstract: A high slope,with height up to 44 m and length up to 2600 m,was filled with the rock-soil mixture material of weathered granite blocks and residual soil after dynamic compaction in Zhuhai.China.The design of slope needs the shear strength of the mixture material.The large-scale in-situ direct shear test was carried out and the strength parameters are as follows:angle of internal friction φ=38°,cohesion c=101.4 kPa,angel of internal friction and cohesion between fill material and natural ground,φ=39.1°,c=108.9 kPa,respectively.The special research on the mixture material shows large cohesion values after dynamic compaction.It can be explained that granite rock-soil mixture material total cohesion consists of the shear cohesion of strong weathered rock,the residual soil's original clay cohesion and the stabilized cohesion after compaction.