Mannitol is the main product when fructose is used as the substrate for heterofermentative lactic acid bacteria under anaerobic conditions. In this study, the mutation of a Lactobacillus brevis strain was induced by atmospheric pressure dielectric barrier discharge plasma and ion beam to improve its mannitol productivity. A positive mutant was selected for its superior mannitol productivity when saccharified Jerusalem artichoke juice was used in selective medium. And it was also confirmed that the mutant strain had high genetic stability. When fermented in 5L fermentor, the mutant could effectively convert fructose into mannitol and the yield of mannitol reached 62%. It was indicated that the mutant strain could be a candidate for industrial mannitol production.