By means of hi situ graft method, polypropylene (PP)-wrapped carbon nanotubes (CNTs) composite were prepared. Infrared spectroscopy (IR) results showed that there was covalent linkage between PP and CNTs via maleic anhydride (MAH) grafting. Owing to the uniform dispersion of CNTs and covalent adhesion between PP and CNTs, the tensile strength of PP-wrapped CNTs composite was higher than that for neat PP by 110% and a 74% increase as compared to the CNTs/PP (with the same CNTs content) composite. The further test showed a strong mechanical behavior with up to 113% increase in Young's modulus of the neat PP. Based on the uniform dispersion of CNTs, the electrical conductivity of PPwrapped CNTs composite increased sharply by up to seven orders of magnitude with 4 wt % CNT fillers. As a result, the volume resistivity was decreased with increase in the CNT content that could be governed in a percolation-like power law with a relatively low percolation threshold. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 3809-3814, 2009