Abstract: The spoIIE gene was knocked out of Bacillus clausii QL-1,and the experiment studied the influence of bacteria sporulation biomass and amylase activity.Electrotransformation of overlapping spoIIE-Cm^r fragments into B.clausii QL-1competent cell made rapid knockout of the spoIIE gene by only one time homologous single exchange. It successfully obtained spoIIE gene deletion strain B.clausii QL-1ΔspoIIE. Compared with the original strain,the sporulation rate of B.clausii QL-1ΔspoIIE decreased to 0.48% at 28 h and the biomass increased by 20% at 20 h. Amylase activity was 5.58 times that of the original strain at 84 h. The maximum biomass of B.clausii QL-1ΔspoIIE strain reached 7.2 mg·mL^-1 by fed-batch fermentation at 80 h,and the amylase activity reached 690 U·mL^-1 at 84 h,increased by 33.30%,compared with that before unfeeding.It was verified that the spoIIE gene was a key gene for the sporulation of B.clausii QL-1,and its deletion had a certain effect on the production of amylase,which was of great significance for the subsequent construction of industrial strains of enzyme activity Bacillus.