Abstract: One strain（MF-3-2） producing amylase was isolated on starch screening medium from the soil around the flour factory, Anyang City. By observing the form of the morphology, gram straining and amplification of its 16S rDNA sequence, the strain MF-3-2 was identified as Bacillus subtilis. After shaking culture, the enzymatic properties were studied by using the crude enzyme. The amylase exhibited maximal activity at pH 6.0 and 65 ℃,and was pH adaptability（＞70% activity at pH 4.8～6.0）. Optimal growth of the strain occurred at 40 ℃ and pH 6.5.The optimization of fermentation conditions were used in this study. The results showed that the optimal medium composing of potato starch, soya bean meal, C/N ratio（1:15）, initial cultural pH 6.0, culture volume 10%, inoculum age 10 h, inoculum size 5%, revolving speed 200 r/min, 30 ℃ fermentation 48 h. On the optimal culture condition, the maximal enzyme production was 86.8 U/mL, which was 35 folds of that before optimization. Medium-temperature amylase produced by this bacterium showed high acid adaptability. So the medium-temperature amylase of the strain has great development potential and application in industrialization.