Abstract: Addition of propanol during erythromycin fermentation with in shake flask improved the titer by 49.3%.Propanol was found to increase the specific activity of propionate kinase,but it had no(influence) on the specific activity of propionyl-CoA synthetase.Addition of Cu~(2+) and niacinamide,(increased erythromycin) titer by 24% and 17%,respectively.Using HPLC,organic acid in the broth were measured;it was suggested that the fermentation process can be divided into three phases: accumulative phase,transitional phase and production phase.In production phase,the productivity of erythromycin was the highest.