Graphite oxide (GO) dispersion liquid was prepared with graphite, concentrated sulfuric acid, potassium permanganate and hydrogen peroxide as main raw materials and by Hummers method. Then GO powder was obtained by freeze drying of GO dispersion liquid. The polypropylene (PP)/GO composites were prepared by mixing of melt PP and GO powder. The microstructure and performances of GO and PP/GO composites were characterized using various testing methods such as FTIR, AFM, TEM, XRD, DSC and conductometer as well as oxygen index determinator. The results indicated that the GO can uniformly distribute in the PP matrix with double layers result in forming compact and even microstructure in PP/GO composites. The mechanical properties, heat-resistant property, flame resistance and thermal conductiveof PP/GO composites have a significant improving compared with the control sample (pure PP resin). When GO dosage is 0.4% by PP mass, the tensile strength, flexural strength and impact strength of the GO/PP composites have an increase rate of 29.6%, 33.6% and 62.7% compared with the control sample, respectively. Meanwhile, its melting point increase to 174.2℃ from 154.5℃, and its thermal conductivity has an increase rate of 205.3%, and the limiting oxygen index increase to 27.6 from 18. The research results indicated that the performances and application fields of PP will be improved by forming composites with GO nanosheets.