A synchronous rectifier control circuit an includes a current transformer (CT), a bridge rectifier, and a comparator, where the CT is connected in series to a secondary side, performs sampling on a loop current of the secondary side to obtain a current detection signal, and outputs the obtained current detection signal to the bridge rectifier; the bridge rectifier acquires a secondary-side sampling current according to the current detection signal, and outputs the secondary-side sampling current to the comparator so that the comparator generates a voltage difference; and an output signal of the comparator turns over so as to control on and off of a synchronous rectifier transistor. In this way, high-speed and high-precision control over a synchronous rectifier transistor can be implemented. The control is simple and is low in cost.