The invention aims to realize that a control mode of primary side feedback is added into an asymmetric half bridge type flyback converter in a non-complementary DCM mode. For the asymmetric half bridge type flyback converter working in the non-complementary DCM mode, primary side inductance is released and is not clamped by an output end at the moment of finishing primary side excitation energy resetting. At the time, the primary side inductance, resonant capacitance, leakage inductance, and parasitic capacitance between the drain and the source of an MOS transistor start resonance oscillation; and at the moment of oscillation starting, a voltage between the drain and the source of the MOS transistor forms an "inflection point", voltages on two ends of the primary side inductance reflect voltage changes of the output end, voltages ontwo ends of an auxiliary winding have similar changes, an oscillation starting direction is just opposite to the direction of the voltages on the two ends of the primary side inductance due to a dotted terminal winding relationship, and if the inflection point is detected through the auxiliary winding and inflection point information is transmitted to a controller, the detection and control of an output voltage can be realized. Compared with the prior art, relatively high output voltage precision, linear adjustment rate and load adjustment rate of the converter can be ensured; and meanwhile, zero voltage switching (ZVS) of a primary side switch tube can be realized, the working frequency of the converter can be increased, the efficiency of the converter can be improved, and the volume of a complete machine is reduced.