Silica and carbon black have been widely used as the main reinforcing fillers for improving the properties of natural rubber (NR). In a silica-filled rubber compound, it is known that the low compatibility between NR and silica affects the mechanical properties of rubber products. In order to overcome this drawback, the functionalized saponified NR (FSPNR) was carried out by grafting acrylamide (AM) onto the saponified NR (SPNR) under UV radiation as a continuous process. An increasing in the bound rubber content and Mooney viscosity was found as an increasing AM content. Storage modulus at low strain amplitude of the silica-filled FSPNR was lower than that of the raw NR. In addition, SEM micrographs showed the good dispersion of silica in FSPNR. These confirmatory evidences indicate the improvement of rubber-filler interaction and the reduction of filler-filler interaction by functionalization under UV radiation.