Abstract: Atmospheric and room temperature plasma(ARTP) Bacillus cereus was used to screen the strains with increased enzyme activity. The results showed that culturing Bacillus cereus in the seed solution for 6 hours could reach the middle and late logarithmic phase. When the mutagenesis time of normal temperature and atmospheric pressure plasma was 60 s, the lethality of Bacillus cereus reached 85%. A mutant strain with a 13.19% increase in chitosanase activity was screened. Then the stability of the enzyme activity was verified. The average enzyme activity after six generations of culture was 9.643367 U/mL, and the fluctuation was within 5%, indicating that its enzyme production was high and the stability was strong, and it could be used for subsequent starting strains. After the mutagenesis, the strain was observed by electron microscope, and it was found that the morphology of the colony did not change significantly, but the individual morphology of the strain had changed, and it was slenderer than the original strain, which proved that the increase in enzyme activity was the effect of ARTP mutagenesis.