The invention discloses an alternating current-direct current converting circuit and a control method thereof. The alternating current-direct current converting circuit comprises an input rectification circuit, a primary side input filter capacitor, a primary side inverter circuit, a drive circuit, an isolation transformer, an auxiliary side rectification circuit, an auxiliary side capacitor and a control circuit, wherein the control circuit is connected between the auxiliary side output filter capacitor and the drive circuit, the drive circuit is connected with the primary side inverter circuit, the primary side inverter circuit and the primary side input filter capacitor form a loop to form a clamping resonance circuit, and inversion switching tubes work in a no-voltage switching state. The auxiliary side rectification circuit has two work modes of forward and flyback, and the first and second inversion switching tubes in the primary side inverter circuit are used as inversion switching tubes or clamping switching tubes according to work periods. According to the alternating current-direct current converting circuit and the control method thereof, diode loss in the rectification loop can be reduced, soft switching of the inversion switching tubes is achieved, voltage stress and switching loss of a primary side switching tube and an auxiliary side rectifier diode are reduced, and efficiency is improved.