The reinforcing effect of white carbon black on various rubber is superior to other white fillers, second only to carbon black. Compared with the vulcanized rubber filled with carbon black, the silica/rubber composite has the advantages of good insulation, low heat generation, high tear strength, low rolling resistance and wetting resistance, etc. In the composites reinforced by silica, silica particles usually exist in the form of loose "nebulae" secondary aggregates. However, SiO2 is a polar particle with poor compatibility with non-polar polymers, and has a strong tendency of adsorption and aggregation. Therefore, silica particles always tend to secondary adhesion, resulting in hydrogen bond association, and it is difficult to evenly disperse in rubber during mixing, and the ideal composite effect can not be achieved. Therefore, it is necessary to modify the surface of SiO2 to improve its compatibility and adhesion with the polymer, so as to prepare nanocomposites with good dispersion and strong interfacial interaction. For this reason, silane coupling agent is often added to the surface modification of white carbon black to make up for its lack of performance, increase its compatibility with rubber matrix, and weaken the packer-filler interaction. The chemical modification of silane coupling agent can improve the interaction between the surface of silica and the polymer and weaken the packer-filler interaction. Bis -[3-(triethoxy silicon) -propyl] tetrafulfide compound is commonly used as surface modification silane coupling agent. The coupling agent reacts with the hydroxyl group on the surface of nano-SiO2, reduces the amount of hydroxyl group on the surface of SiO2, changes the physical and chemical properties of the surface of SiO2, changes it from hydrophilic to hydrophobic, and improves the compatibility and binding between it and rubber. The influence of silane coupling agent on the basic properties of natural rubber composites, such as vulcanization property, mechanical property and stress softening effect, is obviously related to the particle size of silica.