Abstract: In order to increase the yield of Fengycin, Bacillus YA-215 was used as the starting strain in this study to obtain high-yield Fengycin mutants through compound mutagenesis (UV mutagenesis, ARTP-LiCl mutagenesis) breeding. The optimum fermentation conditions were determined by single-factor experiment and response surface methodology. The results showed that a high-yielding Fengycin mutant strain UA397 was obtained through compound mutagenesis, and the whole genome sequencing combined with 16S evolution sample analysis showed that it was Bacillus siamensis. The optimum fermentation process conditions were: Sucrose 25 g/L, peptone 30 g/L, fermentation temperature 37.7 ℃, fermentation time 37.8 h, inoculum size 5.01%. Under these conditions, the Fengycin yield of Bacillus siamensis UA-397 was 517.09 mg/L, which was 4.575 times the Fengycin yield of 113.02 mg/L of the wild type without optimizing the fermentation conditions. This study laid the yield basis for the application of antibacterial lipopeptide Fengycin in the fields of food, medicine and biological control.