Abstract: Based on the K-E model and three-dimensional fractal theory, the contact point of the contact surface was extended to an ellipse, and a fractal model of the contact thermal conductance of the joint surface was established considering the elastic, elastic-plastic and plastic deformation mechanism of the semi-ellipsoid asperity. Based on the built model, the effects of elliptical eccentricity, fractal parameters, and normal load on the contact thermal conductance of the joint surface are studied, and the simulation results show that the contact thermal conductance of the interface in which the asperity is semi-ellipsoid increases with the increase of elliptic eccentricity, the fractal dimension, normal load and contact ratio, but decreases with increase of the fractal roughness parameter. Compared with the contact thermal conductance of hemispherical asperity, the built model is more suitable for the case of large normal load. The simulation results of the built model are also compared with the experimental data to verify the correctness of the built model, which provides a certain theoretical reference for solving the contact thermal conductance of the joint surface in practical engineering.