The effect of oxygen supply on adenosine production of Bacillus subtilis was studied using 50L fermentor with the air saturation at 5%,10%,20% and 30%.We found that the concentration of the critical dissolved oxygen in the industrial strains was 10%～20%.The relationship among strain growths,oxygen uptake rate in the process and dissolved oxygen(DO) tension on adenosine accumulation was analyzed.The results showed that during the adenosine fermentation of Bacillus subtilis,it was better to control DO at 10%～20% than at 5% and 30%.We found that the concentration of pyruvate at the final time of fermentation was higher under low oxygen condition than that under high oxygen condition.Based on the results,a strategy of two stages for DO manipulation was proposed.With this strategy,the adenosine accumulated in 50L fermentor ultimately reached 20.1g/L.