In this paper, we study the effect of changing concentration of nano-zinc oxide in nano-zinc oxide polypro-pylene fiber on its antimicrobial ability. The experimental result indicates that with a concentration of 1.5% nano-zinc oxide, the nano-zinc oxide polypropylene fiber is of great antimicrobial ability. Comparing the antimicrobial ability of polypropylene fiber with nano-zinc oxide and micronized zinc oxide, it shows that nano-zinc oxide has a better antim-icrobial ability in polypropylene fiber than micronized zinc oxide. Moreover, nano-zinc oxide polypropylene fiber has a better antimicrobial ability than nano-zinc oxide polypropylene plastic film. In conclusion, nano-zinc oxide is an ideal antibacterial additive for polypropylene fiber.