An intelligent equalizing battery charger having equalization charging circuitry is disclosed, comprising an insulating switch-type DC to DC converting circuit, a microprocessor monitoring/calculating control circuit, and a charging battery set wherein the insulating switch-type DC to DC converting circuit is composed of a power supply switch circuit, an insulating transformer, and a rectification converting circuit. The microprocessor monitoring/calculating control circuit includes multiple switch elements and a charging control microprocessor. Via the aforementioned structure, each individual cell of the charging battery set can be appropriately charged in equalization, which can not only increase the charging/discharging times of the battery set, but also efficiently extend the battery life in application.