Abstract: Objective: The amylase-producing strain screened on the surface of Yunnan Malong C3F-2016 tobacco leaves were used as the starting strain to mutagenically select high amylase-producing strain and to study the enzymatic properties before and after mutagenesis. Methods: The amylase-producing strain were selected by ARTP technique and the amylase activity was determined by the 3,5-dinitrosalicylic acid (DNS) method before and after mutagenesis, and the effects of different temperatures, pH, metal ions and UV light on the amylase activity were investigated. Results: A mutant strain Bacillus koreensis FS-103 was selected by mutagenesis with improved enzyme activity and stable transmission, and its amylase activity reached 9050 U/mL, which was 90% higher than that of the starting strain. The optimum action temperature of amylase produced by the high-yielding mutant strain FS-103 was 60 ℃ and the optimum action pH5.5, with good stability between 40 and 50 ℃ and pH5~6, Ca²⁺ and Mg²⁺ had a promoting effect on amylase activity, and the effect of UV irradiation on amylase activity was weakened. Conclusion: This method of mutagenic selection of amylase-producing strain was feasible and lays the theoretical foundation for the research and development of enzyme preparations by this type of strain.