To solve the problems of nonlinearity, strong coupling and large lag in the microbial degradation process of fermentation tank, a decoupling control method of fermentation tank based on fuzzy gray wolf PID algorithm was proposed. First, the control system model of the fermentation bin is identified, and the coupling effect of temperature and humidity generated in the control process is eliminated through dynamic decoupling compensation. Then, combining the advantages of PID and fuzzy control, the fuzzy PID control system model is established. Finally, the fuzzy PID initialization parameters are optimized by using the iterative optimization ability of the gray wolf optimization algorithm. The simulation results show that, compared with the traditional control method, the proposed control strategy reduces the temperature loop regulation time from 1 623 s to 596 s, the relative humidity regulation time is reduced by 910 s, and has a better decoupling effect, which can effectively realize the accurate control of degradation environment.