Abstract: In order to predict the susceptibility of equipment under electrical fast transient/burst （EFT/B） test during its early design stage,it is essential to set up the equivalent circuit of the EFT/B generator and its coupling/decoupling network. In order to fit the revised edition of IEC standard,a systematic method was presented to model the equivalent circuit of EFT/B pulse generator. Firstly,an analytical expression was presented to express the generator’s charging and discharging process under open-condition （1 kΩ）,which all coefficients could be determined according to the output waveform specified by the manufacturer. Secondly,with adoption of the step source,the transfer function of the pulse forming network in Laplace domain was deduced,which was ready for the network synthesis. Based on above discussion,the parameterized method and the technique of constant-resistance were adopted for the network synthesis,and then,the equivalent circuit was renormalized and improved to meet the specification under matching-condition （50 Ω）. Finally,the output response of the EFT/B generator through a standardized capacitive clamp was simulated and measured,and the modeling method was validated by comparison between above two results.