To study the influence of the change in elastic modulus of retried cable insulation on interface pressure, the breakdown field strength and dielectric loss angle tangent of cable insulation with different operating years are measured to characterize the electrical properties, as well as the mechanical properties of the elastic modulus at different temperatures.Based on the constitutive theory of hyperelastic materials, the interface pressure of new cable joint assembled on the cable is calculated.Meanwhile, a two-dimensional axial simulation model of the cable joints is established, and the axial distribution of interface pressure is analyzed.The comparisons between simulation and theoretical results show that the error of the interface pressure between the cable body and the joint is not more than 3.2% by using the two-dimensional axial simulation model.The accuracy of the simulation model can provide reliable data for studying the interface pressure distribution on the joint axis maximum.Although the electrical performance of the insulation layer of the cable of different operating years is different, and the difference of cable insulation elastic modulus with different operation year is 29%, but the interface pressure changes only by 0.275%.Therefore, when the new cable joint assembled on the old cable, the interface pressure is sufficient enough.