A method for regulating a temperature of a magnetron, comprising: acquiring an input power (Pin) and an input voltage (Vin) of a variable-frequency power supply being configured to drive the magnetron to operate; calculating the output power (Po) of the variable-frequency power supply according to a corresponding relationship between the input power (Pin) and the input voltage (Vin) of the variable-frequency power supply and a power efficiency (Eff) thereof; determining an equivalent resistance of the magnetron; characterized in that the method further comprises: determining an anode voltage (Ebm) applied to two ends of the magnetron according to a first output voltage sampled by a first voltage sampling circuit; determining an anode current (It) flowing through the magnetron according to the output power (Po) and the anode voltage (Ebm) applied to two ends of the magnetron; determining an anode threshold voltage of the magnetron according to the anode current (It), the anode voltage (Ebm) and the equivalent resistance of the magnetron, and regulating the output power (Po) of the variable-frequency power supply according to the anode threshold voltage of the magnetron, in order to prevent the temperature of the magnetron to be over-temperature, wherein the anode threshold voltage of the magnetron is a stabilized voltage of a Zener diode of an equivalent circuit model of the magnetron. acquiring an input power (Pin) and an input voltage (Vin) of a variable-frequency power supply being configured to drive the magnetron to operate; calculating the output power (Po) of the variable-frequency power supply according to a corresponding relationship between the input power (Pin) and the input voltage (Vin) of the variable-frequency power supply and a power efficiency (Eff) thereof; determining an equivalent resistance of the magnetron; characterized in that the method further comprises: determining an anode voltage (Ebm) applied to two ends of the magnetron according to a first output voltage sampled by a first voltage sampling circuit; determining an anode current (It) flowing through the magnetron according to the output power (Po) and the anode voltage (Ebm) applied to two ends of the magnetron; determining an anode threshold voltage of the magnetron according to the anode current (It), the anode voltage (Ebm) and the equivalent resistance of the magnetron, and regulating the output power (Po) of the variable-frequency power supply according to the anode threshold voltage of the magnetron, in order to prevent the temperature of the magnetron to be over-temperature, wherein the anode threshold voltage of the magnetron is a stabilized voltage of a Zener diode of an equivalent circuit model of the magnetron. determining an anode voltage (Ebm) applied to two ends of the magnetron according to a first output voltage sampled by a first voltage sampling circuit; determining an anode current (It) flowing through the magnetron according to the output power (Po) and the anode voltage (Ebm) applied to two ends of the magnetron; determining an anode threshold voltage of the magnetron according to the anode current (It), the anode voltage (Ebm) and the equivalent resistance of the magnetron, and regulating the output power (Po) of the variable-frequency power supply according to the anode threshold voltage of the magnetron, in order to prevent the temperature of the magnetron to be over-temperature, wherein the anode threshold voltage of the magnetron is a stabilized voltage of a Zener diode of an equivalent circuit model of the magnetron.