Abstract: The characteristic impedance and the transfer function are two important parameters in the electromagnetic transient time-domain simulation model of the multi-conductor transmission line. In this paper, taking the lossy frequency-dependent uniform double-conductor transmission line as the research object, the coupling amount of the transmission line is decoupled by using the phase-mode transformation. Then, in the mode domain, the time-domain equivalent circuit of the characteristic impedance is obtained by using the Pade approximation and the Foster circuit model. Simultaneously, the approximate function of the transfer function is got by using the Laplace inverse transformation and the Prony approximation. Based on the equivalent circuit and the approximation function, the electromagnetic transient time-domain simulation model of the double-conductor transmission line is established by adopting the MATLAB programming. Finally, this time-domain simulation model is used to achieve the voltage responses at the beginning and the terminal ends of the transmission line under the step excitation. The simulation results are compared with those using the PSCAD/EMTDC software to verify the time-domain model in this paper.