[Objective] The aim was to optimize the fermentation conditions of acid resistant α-amylase producing strain. [Method] Based on the selection of an acid resistant α-amylase producing strain,the fermentation conditions including C,N contents and initial pH of culture medium,seed age,inoculum size,rotation speed of shake flask and fermentation temperature were optimized. [Result] The optimum fermentation conditions for acid resistant α-amylase producing strain were：seed age 14 h,inoculum size 8%,initial pH 5.5,fermentation temperature 35 ℃,rotation speed 150 r/min,the volume of inoculum broth 25 ml,C content 1.0% and N content 0.5%. [Conclusion] Under the optimum fermentation conditions,α-amylase activity reached 31.4 U/ml,which was 65.3 % higher than that before optimization.
