Topsoil slip, landslides and other engineering disease are likely to occur when granite residual soil is directly used as sub grade filling. In order to eliminate the adverse properties of granite residual soil，the grain composition of granite residual soil of Nanyue Mountain Area in Hunan Province was analyzed, and it shows that granite residual soil belongs to the sandy clay. In order to improve the performance when granite residual soil was used as sub grade filling, it was improved with different admixture of cement. When the compaction degree of granite residual soil is 90%, Laboratory triaxial test and laboratory disintegration test were conducted with the SLB-1 triaxial and permeability apparatus and the homemade disintegration test apparatus. The shear strength and disintegration test of improved granite residual soil shows that the shear strength and the disintegrating conditions under the influence of water was gradually improved with the increase of cement content. The shear strength was greatly improved and resistance of disintegration gets a better improvement with 6% cement content. It can also achieve the purpose of improving local granite residual soil in practical engineering.