Abstract: Due to the excellent mechanical, electrical and thermal properties, carbon nanotubes (CNTs) are widely used in the research and preparation of high-performance composite. However, with the high aspect ratio, high specific surface energy and strong van der Waals force, CNTs intend to form agglomeration during the preparation process, causing a decrease in the mechanical property of the composite material at high concentration. In order to accurately characterize the tensile mechanical property of CNTs enhanced epoxy nanocomposite (CNTs/EP) nanocomposite, the tensile mechanical properties of different kinds of CNTs/EP were characterized by experiment and finite element analysis. Considering the influence of agglomeration on the material parameter of epoxy, a method for reducing the materials parameter of epoxy in the agglomeration region was proposed to improve the numerical analysis method of agglomeration distribution model. The results show that the uniform distribution numerical analysis method can accurately predict the tensile strength and elastic modulus of CNTs/EP at a low content of 0.5wt%. The agglomeration analysis method accurately predicts the tensile mechanical property, the error of elastic modulus and tensile strength of CNTs/EP are no more than 5% at a high concentration of 1.5wt%.