In this article, we focus on the ultraviolet (UV) shielding efficiency for poly(p-phenylene-2,6-benzo-bisoxazole) (PBO) fiber with zinc oxide (ZnO) nanoparticle/epoxy hybrid coating. ZnO nano particles were initially functionalized with silicon coupling agent for improving their dispersion and surface reactivity, and then they were hybridized with epoxy resin by grafting on the ZnO nano particles. The hybrid reactions have been indicated by means of Fourier transform infrared spectrometer (FT-IR). Its UV light shielding effect of the hybrid coating on PBO fiber properties has been studied using ultraviolet spectrum, tensile test, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Results showed that the surface topographic, the surface polymer structure, and the tensile strength of coated PBO fiber were less declined than that of uncoated fiber by UV light. From these results, the nano-ZnO hybrid sizing had good UV-aging shielding efficiency for PBO fiber. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 2468-2476, 2011