System and method for controlling synchronous rectification. For example, the system for controlling synchronous rectification includes: a switch including a first switch terminal configured to receive a first voltage, the switch further including a second switch terminal and being configured to be closed or opened by a control signal; a voltage generator configured to receive a second voltage from the second switch terminal and generate a third voltage based at least in part on the second voltage; a filter circuit including a resistor and a capacitor, the filter circuit being configured to receive the second voltage from the second switch terminal and generate a fourth voltage based at least in part on the second voltage; a first comparator configured to receive the third voltage and the fourth voltage and generate a first comparison signal based at least in part on the third voltage and the four voltage.