α-amylase can hydrolyze α-1,4 linkages in starch and related carbohydrates under hyperthermophilic condition (~ 100°C), showing great potential in a wide range of industrial applications, while its relatively low productivity from heterologous hosts has limited the industrial applications. , a gram-positive bacterium, has been widely used in industrial production for its non-pathogenic and powerful secretory characteristics. This study was conducted to increase production of α-amylase in through three strategies. Initial experiments showed that co-expression of molecular chaperone peptidyl-prolyl -trans isomerase through genomic integration mode, using a CRISPR/Cas9 system, increased soluble amylase production. Therefore, considering that native α-amylase is produced within a hyperthermophilic environment and is highly thermostable, heat treatment of intact culture at 90°C for 15 min was performed, thereby greatly increasing soluble amylase production. After optimization of the culture conditions (nitrogen source, carbon source, metal ion, temperature and pH), experiments in a 3-L fermenter yielded a soluble activity of 3,806.7 U/ml, which was 3.3- and 28.2-fold those of a control without heat treatment (1,155.1 U/ml) and an empty expression vector control (135.1 U/ml), respectively. This represents the highest α-amylase production reported to date and should promote innovation in the starch liquefaction process and related industrial productions. Meanwhile, heat treatment, which may promote folding of aggregated α-amylase into a soluble, active form through the transfer of kinetic energy, may be of general benefit when producing proteins from thermophilic archaea.