Abstract: This papter uses the compaction method for preparing the remolded red clay with the addition of nano graphite powder(NGP). It designs the consolidation and undrained triaxial experiment of different dosage of NGP under optimum water content of red clay. The effect of doped with different amount of nano graphite powder on mechanical properties of red clay is analyzed by adopting the method of stress and strain curve, which obtains the rules of shear strength and shear strength index. The improving mechanism is futher analyzed with SEM method. The experimental results show that:with the increase of NGP content, the shear strength and cohesion C increase firstly and then decrease, the internal friction angle \varphi remains basically unchanged. It can be observed that the appropriate amount of NGP has an significantly improvement on the mechanical properties of red clay. The best dosage is between 1% to 2%. The study suggests that the presenting mechanical properties of NGP-red clay is closely related to the effect of the NGP on the pore structure of red clay and the particle adhesion and cementation.