A method and device for regulating a temperature of a magnetron, a controller, a variable-frequency power supply, a system for regulating a temperature of a magnetron, and a microwave apparatus are provided. Wherein, the method for regulating the temperature of the magnetron includes: determining an anode current flowing through the magnetron or an input power of a variable-frequency power supply or an anode voltage applied to two ends of the magnetron, the input power or an output power of the variable-frequency power supply being configured to drive the magnetron to operate; regulating the output power of the variable-frequency power supply according to the anode current or the input power or the anode voltage.