A synchronous rectifier control circuit, comprising: a current transformer CT, a bridge rectifier, a comparator, and a voltage source, wherein: the current transformer CT is configured to be connected in series to a secondary side of a power loop, perform sampling on a loop current of the secondary side to obtain a current detection signal, and output the obtained current detection signal to the bridge rectifier; the bridge rectifier comprises a first resistance and four diodes (D1,D2,D3,D4),and the four diodes are a first diode, a second diode, a third diode and a fourth diode, an anode of the current transformer is connected to an anode of the first diode, a cathode of the first diode is connected to a cathode of the second diode and connected to one end of the first resistance, the anode of the first diode is connected to a cathode of the third diode, an anode of the second diode is connected to a cathode of the fourth diode, an anode of the third diode, an anode of the fourth diode and the other end of the first resistance are connected to ground; a cathode of the current transformer is connected to the anode of the second diode; and characterized in that the comparator comprises a second resistance, a third resistance, a fifth diode,a first bipolar transistor and a second bipolar transistor, an anode of the voltage source is connected to one end of the second resistance and connected to one end of the third resistance, the other end of the second resistance is connected to a collector of the first bipolar transistor, the other end of third resistance is connected to a collector of the second bipolar transistor, a base of the first bipolar transistor is connected to a base of the second bipolar transistor, connected to the collector of the second bipolar transistor through the fifth diode, and connected to the collector of the first bipolar transistor; an emitter of the first bipolar transistor is connected to the cathode of the fourth diode; an emitter of the second bipolar transistor and a cathode of the voltage source are connected to the ground, wherein: the collector of the second bipolar transistor generates an output signal used to control on and off of a synchronous rectifier transistor. the current transformer CT is configured to be connected in series to a secondary side of a power loop, perform sampling on a loop current of the secondary side to obtain a current detection signal, and output the obtained current detection signal to the bridge rectifier; the bridge rectifier comprises a first resistance and four diodes (D1,D2,D3,D4),and the four diodes are a first diode, a second diode, a third diode and a fourth diode, an anode of the current transformer is connected to an anode of the first diode, a cathode of the first diode is connected to a cathode of the second diode and connected to one end of the first resistance, the anode of the first diode is connected to a cathode of the third diode, an anode of the second diode is connected to a cathode of the fourth diode, an anode of the third diode, an anode of the fourth diode and the other end of the first resistance are connected to ground; a cathode of the current transformer is connected to the anode of the second diode; and characterized in that the comparator comprises a second resistance, a third resistance, a fifth diode,a first bipolar transistor and a second bipolar transistor, an anode of the voltage source is connected to one end of the second resistance and connected to one end of the third resistance, the other end of the second resistance is connected to a collector of the first bipolar transistor, the other end of third resistance is connected to a collector of the second bipolar transistor, a base of the first bipolar transistor is connected to a base of the second bipolar transistor, connected to the collector of the second bipolar transistor through the fifth diode, and connected to the collector of the first bipolar transistor; an emitter of the first bipolar transistor is connected to the cathode of the fourth diode; an emitter of the second bipolar transistor and a cathode of the voltage source are connected to the ground, wherein: the collector of the second bipolar transistor generates an output signal used to control on and off of a synchronous rectifier transistor.