The large － scale commissioning of intelligent substations has made electronic current transformer with Ｒogowski coil more widely used． Based on the principle of sensing unit of Ｒogowski coil ，the influencing facfors of its transfer characteristics are analyzed，the transfer function of sensing unit and external integration link is calculated，and its frequency response characteristics are obtained． The ideal experimental model and the actual power grid model are established respectively with Matlab and PSCAD simulation platform． The correctness of the theoretical derivation provides a theoretical guidance for improving the transfer characteristics of electronic current transformer with Ｒogowski coil．