Abstract: Rutile TiO2 silane was grafted with coupling agent onto the surface by in situ polymerzation. The effect of particle size and the dosage of coupling agent was studied.It was found that the smaller the TiO2 particle size and the larger the functionality of the coupling agent, the higher the degree of modification.When the coupling agent was KH-570,the optimal loading was 10 ml.Scanning electron microscopy (SEM) and IR spectra showed that coupling agent and nanoparticles were linked chemically. The surface modification of nanoparticles reduced the agglomeration,and thus enhanced the dispersion.When introduced into PVA film,the mechanical properties and UV resistance were effectively improved.