Due to the significant oxygen requirement during acidic protease production and the relatively low solubility of oxygen in fermentation broth,aeration is critical for bioprocess.Several oxygenvectors,namely acetic ether,oleic acid,soybean oil,n-dodecane and Tween-80,in enhancing acidic protease accumulation and its productivity by Aspergillus niger were examined for oxygen transfer process.Shake flask fermentation were conducted to investigate the effect of different concentrations of oxygen vectors on enzyme production and mycelia growth.The experimental results show that the addition of 2% (V/V) oleic acid can greatly enhance acidic protease accumulation,reduce the residual glucose concentration and stimulate mycelia growth.