The preferred emulsifier was used to emulsify the plasticizer naphthenic oil (NAP), and uniform and stable NAP emulsion was prepared. The NAP-plasticized natural rubber (NR)/silica (SiO2) ...(NAP/NR/SiO2) composite was prepared using the resulting NAP emulsion, NR latex and SiO2 slurry by wet mixing process, and the effects of NAP addition amount on Mooney viscosity, physical and mechanical properties, dynamic mechanical properties, dispersion of SiO2, thermal air aging resistance and flexural cracking property of NAP/NR/SiO2 composites were studied. The results showed that Mooney viscosity of NAP/NR/SiO2 composite was significantly lower than that of NR/SiO2 composite, Payne effect was significantly weakened, and dynamic mechanical properties and proces-sability improved significantly. When NAP addition amount was 10 phr (mass), NAP/NR/SiO2 composite had the best comprehensive performance, and tensile strength of NAP/NR/SiO2 composite decreased slightly, whereas elongation at break increased to varying degrees
