Ultra-high molecular weight polyethylene (UHMWPE) has been regarded as a representative of bio-materials, especially for artificial prostheses for long term knee/hip joint use. In this work, we have produced micro-nano-composites by using graphite (Gr) as filler to increase the mechanical anti-wear property. The dispersion of graphite in the composites matrix and the influence of processing conditions was investigated by octa-screw kneading machine. The experimental results suggested that the elastic modulus of the composites raised by 37-70% with the addition of 2wt% Gr. The bending strength of the graphite filled micro-nano-composites also increased by 21-33%. In addition, the size of Gr on mechanical properties of the composites was affected. In the case of the average 20µm diameter Gr, the elastic modulus of the composites improved by 25% when compared to that of 5µm. In this presentation, we will discuss viscoelasticity and friction properties of Gr filled composites with different Gr size and shape.