In the process of tylosin fermentation,the composition of fermentation medium plays an important role in the transformation of biological components.In this paper,the effects of carbon source,nitrogen source and precursor addition on the content of tylosin components in fermentation medium were studied,and the optimal culture conditions for the stability of tylosin components were discussed.The results showed that 0.15%trimethylammonium glycolide was added to the fermentation broth at the beginning of 4h,and 0.20%sodium malonate was added after 12 h.Taking rapeseed oil as the carbon source,isoleucine,leucine and valine were directly used as nitrogen source supplement at the ratio of 1.0∶1.5∶2.0,and the pH of the fermentation broth was 7.0,the content of tylosin A component was significantly increased,the content of macrocin C was reduced,and the total component was stable.