A switching power circuit for charging a battery can include: four switches extending between two ports of a low-frequency AC input voltage and an energy storage circuit, where the energy storage circuit and a primary winding of a transformer are coupled between first and second nodes, the first node is a common node of the first and second switches, and the second node is a common node of the third and fourth switches; a rectification circuit having an input terminal coupled to a secondary winding of the transformer; a DC-DC converter having an input terminal coupled to an output terminal of the rectification circuit, and generates a charging current; and a control circuit that adjusts the charging current by controlling an operation of the DC-DC converter according to a charging requirement, in order to make an average value of the charging current meet the charging requirement.