The spores of strain producing exopolysaccharide were mutated by N+ ions implantation to obtain a high-yield strain of exopolysaccharide in this study. The used energy and dose during the implantation process was about 10 keV and 60×1014–140×1014 cm-2, respectively. The optimal dose was decided by the livability and mutation rate of the strain. It was found that the curve of survival took a “saddle shape” with increasing N+ ion dose. The best induced mutation action was obtained when the ions implantation dose was 120×1014 cm-2. After the selection and 5 generations of propagation, the mutant strain with high stability was obtained, whose exopolysaccharide yield reached 3.29 g/L, which was about 19.20% higher than that of the original strain, and the fermentation time was decreased by 6 h.Cited