The invention provides a control circuit and a synchronous rectification circuit, the control circuit is used for a switching a power converter. The control circuit is configured between the secondary side of the switching a power converter and the output end of the switching a power converter. The control circuit comprises a linear predicting circuit, a resetting circuit, a charging/discharging circuit, and a pulse width modulating circuit. The linear predicting circuit receives a linear predicting signal from the secondary side to generate a charging signal. The resetting circuit receives a resetting signal to generate a discharging signal. The charging/discharging circuit receives the charging signal and the discharging signal to generate a slope signal. The width modulating circuit receives the linear predicting signal to enable a switch signal and the slope signal to reset the switch signal.