||In this study, PP-CNF composites were prepared by compression molding. To improve interfacial bonding between PP and CNF, PP surface have been modified using the aqua regia(HCl, HNO3). Fourier-transform infrared(FT-IR) spectroscopy was performed to identify the structure of modified polypropylene. Mechanical properties of the PP-CNF composites were investigated using UTM and impact tester. Thermal properties of the PP-CNF composites were investigated using TGA and DSC. Then, MPP-CNF was prepared according to the modifying conditions.