Abstract: 【Objective】 In order to obtain the low-temperature amylase gene and its related functions, and better apply it in industrial production. 【Methods】 Cloning of the low temperature ɑ-amylase gene from the starting strain LA7 to BL-21 (DE3). Other known low temperature ɑ-amylase gene was homology analysis,design specific primers,and C13 fragment was obtained by PCR amplification.Then clone it to pMAL-2X,Convert it to BL-21 (DE3),and screening blue and white spots.The ɑ-amylase gene was verified by PCR and double enzyme digestion of EcoRⅠ and Hind Ⅲ,the highly expressed bioengineering strain pMAL-2X- C13was obtained.The site directed mutagenic primers was design,take pMAL-2X- C13 as the template,three mutant strains of low temperature amylase gene C19, C29 and C43 were obtained. 【Results】 SDS-PAGE test result display that the molecular size of the protein is 114 kD and the protein expression of mutant strain C19 was higher than that of strain pMAL-2X- C13. 【Conclusion】 The protein expressed of mutant strain C19 more than the original strain pMAL-2X- C13.It provides a scientific and theoretical basis for the future application of the engineering bacteria in industrial production.