Amylase is widely used in paper industry and the demand for amylase has been increasing, high-yield amylase strains could be mutagenized and screened to solve this problem. Three strains of amylase-producing bacteria were screened by transparent circle method from soils. In order to enhance the production of amylase, they were mutag- enized by ultraviolet light and ultrasonic. The result showed that the proper time of these strains exposed to ultraviolet light was 30 s and the suitable distance was about 15 cm. Among these three strains, strain C1 and S were better mutag- enized and their transparent circles were up to 3.00 under the above condition. The proper time for ultrasonic mutagen- esis was 20 min, the transparent circles of strain C1 and S were up to 2.50 under this condition. It could be concluded that both ultraviolet light and ultrasonic mutagenesis could improve the production of amylase. The effect of ultraviolet light mutagenesis was more stable than ultrasonic mutagenesis while the production of amylase after ultraviolet light mutagenesis was higher than that of ultrasonic mutagenesis.