The invention relates to a large power energy storage current transformer and a main circuit thereof. A main circuit of the current transformer includes a bidirectional AC/DC current transforming module which is composed of two three-phase full-bridge IGBT power transforming units connected in parallel, the AC side of the bidirectional AC/DC current transforming module is used for connecting an electrical network, and the DC side is used for connecting an energy storage medium. Conventional two-stage transformation is substituted by one-stage transformation, problems of high manufacturing cost, complex control and low reliability of a present large power energy storage current transformer adopting two-stage transformation are solved.