Abstract: Objective: Response surface analysis ( RSA) was used to optimize the fermentation conditions for improving the production of cecropins. Methods: Plackett- Burman factorial design was applied to evaluate the effect of eight different fermentation conditions on the production of cecropins-produntion strain KJ05, and the RSA was carried out to optimize the fermentation conditions.Results: Among the variables, glucose, pH and inoculation amount were found to be the most significant variables.The experiment results showed that by using the optimal condition the average titer of cercropins reached 12852U /mL, and the optimal condition was as follows: glucose was 5.7%, the inoculation amount was 5.6% and the pH was 6.4.The optimal fermentation conditions were tested in 500L fermentor, the titer of cecropins reached 15520U /mL. Conclusion: The experiment results showed that the fermentation production of cecropins was increased by 30.7% compared with the unoptimized conditions.