Polymer-based nanocomposite films have been widely used as dielectrics in advanced electronic packaging filed. The adjustable physical properties are desired to follow theadvancement of the electronic packaging technology. A UV curing resin system, which has advantages of fast curing, energy saving and environmental friendly compared with the thermal curing composition, has great application potential in high-tech fields. In this work, the acrylic modified epoxy resin mixed with UV light curing accelerator are used as the polymer matrix. To reduce the coefficient of thermal expansion and dielectric loss, nano silicon oxide (SiO2) is used as fillers to prepare the composites. The UV curing behaviors of the pure epoxy and the SiO2 -filled composition are studied. In order to analyse the nanoparticles effect on the UV curing performance, a UV light scattering model is proposed based on the UV absorption spectrum. The relationship between the dielectric, mechanical properties and curing degree, filler content of the cured composites is established. This study provides a guide to design high performance UV curing nanocomposites.