A new macromodel of lossy transmission lines is presented for the time domain simulation of the interconnection systems in the high speed VLSI.It is based on the method of characteristics（MC） with some modification.By approximating the Telegrapher’s equations in the frequency domain

the time domain macromodel is obtained and a set of recursive formulas is derived for computing the voltages and currents at two ends of the lines.The algorithm is useful for both delay and crosstalk estimation and can be used to evaluate transient responses of high speed interconnection circuits.The new macromodel concerns only the quantities at two ends of the lines

so the algorithm based on it consumes less computer time and less memory in comparison with other methods.It is of high accuracy and absolute stability.