Abstract: Natural rubber composites were prepared by replacing 0,2,4,6,8 part (mass parts per 100 mass parts of natural rubber) carbon black with 0.5 part carbon nanotubes (CNTs) in the basic formula. The effects of CNTS on the static mechanical properties and dynamic properties of natural rubber composites were investigated. The results show that with the increase of carbon black parts replaced by CNTs, the hardness of composites decreased, the tensile strength increased first and then decreased and then increased, the fracture elongation decreased first and then increased, and the 100% constant elongation stress increased first and then decreased. The composite static mechanical properties of the composites after replacing 2 part carbon black with 0.5 part CNTs were the best, and the tensile strength and 100% constant elongation stress were both the highest, which were 13.52% and 8.47% higher than those of the composite without replacing carbon black with CNTs, respectively. With the increase of the parts of carbon black replaced by CNTs, the root mean square of dynamic stiffness of the composites decreased first and then increased. The root mean square of dynamic stiffness of the composite after replacing 2 part carbon black with 0.5 part CNTs was the smallest, which was 12.94% lower than that without replacing carbon black with CNTs. In this case, the composites had the best high-frequency dynamic properties. The tensile strength and 100% constant elongation stress were positively correlated with high-frequency dynamic properties, while fracture elongation and hardness were not significantly correlated with high-frequency dynamic properties.