The level of penicillin fermentation production depends on the strain capacity and the control of the fermentation process. The process control of penicillin fermentation is difficult because of its long cycle and many influence factors. Although the strain and equipment is the same, fermentation level can differ by more than 15% because of the difference of process control. The metabolic directions were effectively controlled, metabolic abnormalities were avoided and low batches were prevented through the control of the seed quality, careful operation and inspection in the moving process, control of pH value, ammonia nitrogen and other important parameters, dynamic adjustment of feeding amount,etc.The difference between fermentation batches could be reduced and the overall level by about 5% could be improved.