The invention belongs to the technical field of electronics and mainly provides a switch power supply system, a control circuit and device for the switch power supply system, which are applied to thecontrol circuit of the switch power supply system. A first overvoltage protection signal output via a first overvoltage protection module and a second overvoltage protection signal output via a secondovervoltage protection module are processed through a logic module to obtain corresponding pulse width modulation signals; a drive module is controlled to output corresponding drive signals to control on-off of a switch module through the pulse width modulation signals; when the input voltage of the switch power supply system is high voltage, the consistency of the output overload protection points of the switch power supply is improved, thereby solving the problem that in the existing AC-DC switch power supply, the inductive current enters a continuous conduction mode while the output load increases; when the input line voltage of the AC-DC switch power supply system increases, the consistency of the output overload protection point of the inductive current is reduced, thus increasing the error of the inductive current and bringing greater potential risks to the AC-DC switch power supply and the rear-end circuit.