A control circuit, a control method, and a power supply device are provided. The control circuit includes an obtaining sub-circuit, adapted to obtain a voltage signal from a reverse surge current when the reverse surge current appears on a primary side of a switch power circuit of a synchronous rectification circuit; a maintaining sub-circuit, adapted to continuously output a first control signal in a preset first time period when the voltage signal is greater than a preset first voltage threshold; and a control sub-circuit, adapted to control and switch off switch tubes of the secondary side of the switch power circuit of the synchronous rectification circuit according to the first control signal. Thus, a reverse current surge of the switch power circuit of the synchronous rectification circuit can be effectively suppressed, and the safety of a switch power supply of the synchronous rectification circuit can be effectively protected.