Abstract: Temperature control of medium frequency induction furnace generally has time lag nonlinearity, and the uniformity of the melt temperature is poor, which easily affects the melting quality. For this, a control system for melting temperature optimization of medium frequency induction furnace was developed using Siemens S7-1200 PLC.Smith predictor was used to compensate the time delay term, while fuzzy PID was used to improve the robustness of the nonlinear control. 6 thermocouples for the furnace was configured, and with the allowable hump height, the feed frequency was controlled by the maximum temperature difference feedback, and the stirring intensity was adjusted to make the melt temperature uniform.The test shows that the melting temperature control accuracy is< 10℃, the uniformity of the melt temperature is< 5℃, which meets the needs of the furnace and is helpful to improve the stability of the melting quality.