Abstract: In order to analyze the road characteristics of granite residual soil, the influence factors are examined and granite residual soils in Hunan are collected for laboratory tests. Through thin section and XRD experiments, mineral composition and basic structures of granite residual soil are obtained and the results indicates that this kind of granite residual soil has a high content of mica that behaves a laminated structure. Based on a large number of statistics and experiments, this paper studies the change in the road characteristics of the residual soil from three factors, including the particle size composition, compaction energy and water content. The results reveal that the fine sand content is the key influence factor on the soil water-bearing property and the coarse grain content has an exponential relation with CBR. Moreover, the particular particle size composition makes good sense to the road characteristics of granite residual soil. With the rising compaction energy, the head and the tail growth (decent) rate of the maximum dry density are large and the middle is small, contrary to the optimum moisture content. The max CBR value increases linearly and then basically remains unchanged as the compaction energy rises. Combined with the compaction energy, water content has a critical value and is less than this value. CBR is positively correlated with the compaction energy and if not, CBR is negatively correlated with the compaction energy.