The effects of organic nitrogen sources on the fermentation of L-valine were studied with L-valine-producing strain Corynebacterium glutamicum XV0505.Corn steep liquor was selected as the appropriate nitrogen source instead of soybean hydrolysates to reduce the cost of fermentation.The effects of initial concentration of corn steep liquor in fermentation process on biomass,glucose consumption rate,yield of L-valine,accumulation of byproduct and ammonia consumption rate were studied by carrying out fed-batch fermentation.The optimal initial concentration of corn steep liquor was also determined.The effects of the combined agents,biotin and corn steep liquor,on overproduction of L-valine were also studied,and the concentration of biotin was optimized.Compared with those of the original process,the biomass and L-valine production from the improved process were increased by 13.2% and 18.5 % respectively.