In one embodiment, a synchronous rectification control circuit in a flyback converter, can include: a first control circuit that receives a drain-source voltage signal of a synchronous rectifier switch and a flyback converter output voltage, and generates a first control signal based on a conduction time of a primary-side power switch; a second control circuit configured to receive the drain-source voltage signal, and to generate a second control signal; when the primary-side power switch is turned off, and the first control signal is greater than a threshold value, the second control signal controls a switching operation of the synchronous rectifier switch; and when the primary-side power switch is turned off, and the first control signal is less than the threshold value, the synchronous rectifier switch is configured to stop operation, before the primary-side power switch is turned on again.