Abstract: A study was made on Bacillus subtilis is strain BS059 with the production of α- acetolactate decarboxylase by the technology of UV irradiation (λ=260nm，W=15w). The result showed that optimal mutation effect was at the irradiation time of 50 seconds. After several screening tests, two mutant strain was named BS059-15 and BS059-22 whose enzyme activities was 107.62% and 162.25% higher than the original strain BS059 respectively. Then it was found that the yield of α-ALDC by the strain BS059-15 and BS059-22 were stable through successive transfer of culture.