The invention discloses a variable switching frequency control method for a flyback inverter. The method comprises the steps of defining a switching period threshold of a switch S5 as T1 and a turn-ontime threshold of the switch S5 as Ton1; when a switching period of the switch S5 is greater than or equal to T1, adopting a quasi-resonant switching mode; when the switching period of the switch S5is smaller than T1, judging whether the turn-on time of the switch S5 is greater than Ton1 or not, if so, adopting a fixed-frequency switching mode; and if not, adopting a variable-frequency switchingmode. The characteristics of a switch tube are fully considered; the influence of the switching loss in a circuit and the influence of a switching dead zone on an output current waveform harmonic wave are considered; the control logic is simple; meanwhile, a variable-frequency control mode is innovatively launched, that is to say, the switching loss and the output harmonic wave can be effectivelyreduced by adopting a variable-frequency real-time calculation mode; and the defects of the prior art are overcome.