Abstract: Single input single output fuzzy-self-adjusted PID algorithm has many restrictions when applied in tunnelmicrowave heating system because such system has close coupled property. Thus the algorithm of fuzzy decoupling is raisedaccording to the algorithm of fuzzy self-adjusted PID. Such algorithm can decrease or even eliminate the coupling of thevariables in this system. The stability of the system can also be improved. Discussion over the designing of control software isalso included on the basis of the existing hardware platform. The efficiency and effectiveness of the control software is mainly considered in this paper.