Graphene/Polypropylene nanocomposite is a new material and limited research is performed on mechanical properties of such material. A random distribution of the nano particles in the matrix has a special importance in having proper mechanical properties for Graphene/Polypropylene nanocomposites. To have a uniform distribution of the nano graphene in the polypropylene, a method developed by Kalaitzidou, et al. for distribution of exfoliated graphite in polypropylene is used in this research. In this paper, Polypropylene is coated with graphene and then the nanocomposite specimens are made using melt-blending and injection molding. Polypropylene reinforced with 0.5, 1.0 and 2.0 wt% graphene sheets were prepared and their tensile properties are investigated. Good enhancement of Young’s modulus and yield stress at very low graphene contents are achieved. The results indicate that the mentioned method is suitable for fabrication of graphene/polypropylene nanocomposites, which yields a good dispersion of graphene in the polypropylene.