It is difficult to describe the microwave heating procedure with accurate mathematical modeling since it is nonlinear and time-delayed. The existing microwave power control methods generally adjust and control parameters according to the results identified by the system. Because those methods feature a long transition time and low stability, a method of expert-Proportion Integration Differentiation (PID) active control on the source power of microwave is proposed. When 'thermal runaway' is prevented, the database of experts’ control rules is set up in line with such prior knowledge as dielectric properties and reflected power of materials. The control rules are in advance stored in the controller, so the problems of hard real-time control and low accuracy of control in the microwave heating procedure can be solved. Compared with the classical PID control, the simulation findings show that the expert-PID control saves about 70% of time taken to reach the state of being stable, improves the efficiency by 89% and increases the accuracy by 87%.