The invention discloses a switch charging circuit and a power management system. The switch charging circuit comprises a system power end, a battery end, a reference power end, a charging enable signal end, a battery-powered judgment signal end and a switch charging module. The switch charging module comprises a switch charging control logic module, a charging voltage control module, a charging current control module, a pulse width control module and a switch power level. The power management system comprises a first voltage comparison module, a second voltage comparison module, a logic control module, a first voltage maintenance module, a second voltage maintenance module, a first switch unit, a second switch unit, the reference power end, an external power input end, the system power end, the battery end, the switch charging module and a first voltage conversion module. The switch charging circuit and the power management system are simple in implementation and high in charging efficiency.