Abstract: The present invention provides a voltage equalization apparatus and method for a battery system. The apparatus includes: a mutual inductor or a transformer, which includes a primary winding, a magnetic core and multiple secondary windings; a first switch, connected in series with the primary winding, wherein the first switch and the primary winding are connected in parallel with the battery system; a plurality of second switches, respectively connected in series with the secondary windings, wherein the second switches and the secondary windings are connected in parallel with the cells; and a voltage equalization control circuit, configured to: test voltage of each cell in the battery system and control turning off and turning on of the first switch and second switches.