High-performance polypropylene (PP)-based copolymer containing a small amount of reactive functional group was synthesized through copolymerization using a Ziegler-Natta (ZN) catalyst. It was found that a small amount of alkoxysilyl group in the PP chain (comonomer content was under 5.0 x 10^-3 mol%) does not deteriorate the base properties of PP such as melting temperature, crystallinity and so on. However, drastic enhancement in the crystallization rate as well as physical properties was observed in the copolymer. It is suggested that these improvements could be attributed to the reaction of functional groups incorporated in the PP chains.