Photopolymerization of composites still remains challenges due to the light screening effect of the fillers.Here we present a facile method based on upconversion nanoparticles(UCNPs)-assisted photochemistry to achieve efficient photopolymerization of composites.Under a 980 nm near-infrared(NIR)light irradiation,UCNPs are able to convert NIR light into UV and visible light to activate photoinitiators for the initiation of polymerization.With optimal parameters,80×10×5 mm of photopolymerization mechanical splines combined with 10%of glass microspheres were obtained.The flexural strength of the photocured materials using UCNPs as internal lamps were higher than those of the reference cured under traditional blue LED light which means that UCNPs-assisted photochemistry has excellent prospects in the preparation of photocurable composites.