The electric conductivity of CB-HDPE composites has been studied by investigation of the dependence of resistivity upon filler volume fraction after irradiation or at different ambient temperatures. The experimental data can be well fitted to the GEM equation. The parameters, phi (C) and t in the corresponding GEM equations obtained by fitting and L-phi and L-f derived after fitting are analyzed in combination with the dispersion of the components in the composites. SEM study on morphology of the composites find those parameters are closely related to the structure of filler's conductive network and the configuration of the network with polymer matrix.