For a more comprehensive study on the shear strength characteristic of basalt fiber and nano silica reinforced clay,the basalt fiber and nano silica were used as reinforcement materials to be incorporated into Shanghai clay in single or mixed form. The direct shear test was carried out to study the influence of the two materials on the shear strength of Shanghai clay by changing the reinforcement ratio of the two materials. The result shows that: the basalt fiber can effectively improve the shear strength of Shanghai clay , when the reinforcement ratio is 0.5%, the reinforcing performance is the most efficient; the addition of nano silica to Shanghai clay also increases the shear strength, and 1.0% is the best reinforced ratio; the shear strength of fiber-nano silica reinforced clay rise significantly under severe conditions (reinforcement ratio), the combined effect of the 0.5% basalt fiber(by weight) and 1.0% nano-silica(by weight) is the most effective; mixing basalt fiber with nano silica can obviously enlarge clay's cohesion, however the angle of internal friction was slightly influenced.