Waxberry-like poly(acrylonitrile-co-vinyl acetate)/Ag composite microspheres have been prepared simply and directly via a one-step self-assembly approach. The morphology, formation, and catalytic activity of the as-prepared composite microspheres are further investigated. The difference in the solubility among different segments of poly(acrylonitrile-co-vinyl acetate) is the basis of the formation of poly(acrylonitrile-co-vinyl acetate) microspheres, while the -CN groups on the surface of poly(acrylonitrile-co-vinyl acetate) microspheres play an important role in the growth process from poly(acrylonitrile-co-vinyl acetate) microsphere to poly(acrylonitrile-co-vinyl acetate)/Ag composite microsphere. It is found that bulk quantities of composite microspheres with high density of Ag nanoparticles on the surface can be obtained readily by controlling the concentration of AgNO3. The as-prepared composite microsphere exhibits excellent catalytic activity on reduction of p-nitrophenol. This study may shed some light on the self-assembly of other metal/polymer composite microspheres. POLYM. ENG. SCI., 50:1767-1772, 2010. (C) 2010 Society of Plastics Engineers