In this paper a new model of lossy transmission lines is presented for the time-domain simulation of high-speed interconnects. This model is based on Modified Method of Characteristics (MMC). The characteristic functions are first approximated by applying lower-order Taylor series in the frequency domain, and then a set of simple recursive formulas are obtained in the time domain. The formulas, which involve tracking performance between two ends of the transmission line, are similar to those derived by the method of characteristics (MC) for lossless or undistorted lossy transmission lines. The algorithm based on the model can efficiently evaluate transient responses of high-speed interconnects. It only uses the quantities at two ends of the lines, requiring less computation time and less memory than other methods. Examples indicate that the new method is having high accuracy and is very efficient for the time-domain simulation of interconnects in high-speed integrated circuits.