Provided are a power supply circuit, a power supply device and a control method. The power supply circuit includes a primary rectifier unit, a modulation unit, a transformer, a secondary rectifier and filtering unit, a current feedback unit and a current sampling control unit. The power supply circuit removes a liquid electrolytic capacitor at a primary side, and an output current of the power supply circuit has a periodically changing current value. The power supply circuit may determine when the output current is at a peak value based on a feedback voltage outputted by the current feedback unit, such that the power supply circuit may manage and control a size of the peak value of the output current.