With 4,4'-diaminostilbene-2,2'-disulfonic acid (DSD acid) as the luminescent parent and cyanuric chloride as the crosslinking agent, a pendant chitosan oligosaccharide fluorescent oligomer （COS-FBs）was synthesized by nucleophilic substitution reaction. A fluorescent nanoparticle polymer （SiO2/ COS-FBs）was prepared with COS-FBs as material by the improved Stober synthesis method. Its structure, morphology and particle size were studied by FTIR, XPS, TEM and their photophysical properties were studied by UV spectra and photoluminescence. At the same time, the effect of returning to yellow on paper was also investigated by UV aging experiment. The results showed that the synthesized fluorescent nanoparticles （SiO2/ COS-FBs）had regular spherical structure with a particle size of 90 nm. Compared with the fluorescent oligomers without nano modification, UV absorption was broadened, fluorescence intensity was improved, the brightening effect and light stability were nice in the performance of application.