The invention discloses a maximum power factor control method of an intermediate frequency power supply induction heating apparatus. The method has the following steps: a current transformer is used to measure intermediate frequency power supply current; a controller controls impulse by a power inverter to calculate intermediate frequency power supply voltage; phase comparison is carried out on the intermediate frequency power supply current and intermediate frequency power supply voltage and the intermediate frequency power supply power factor is calculated; the controller controls the frequency of the intermediate frequency power supply induction heating apparatus according to the power factor to enable the intermediate frequency power supply induction heating apparatus to maintain the maximum power factor. In the invention, the intermediate frequency power supply induction heating apparatus can maintain the maximum power factor which normally can reach more than 97%.