In this paper, by calculating the fractal dimension, a general method for quantitatively evaluating the space filling degree of the CNT interface surface area is given, and the relationship between the electrical conductivity of the composite material and the mechanical strength is clarified. In addition, we also proposed a method to estimate the space filling degree of the interface surface area through the increase of fractal dimension by controlling various dispersion conditions in the CNTs dispersion process, which is of great significance for the preparation of CNT composite materials.