The effect of dissolved oxygen controlled level on the taxol production by suspended cell culture of Taxus chinensis was examined in shake flasks and in a 20L aerated and agitated bioreactor with a six-flat-bladed turbine. It was found in shake flasks that oxygen supply exhibited significant influence on the production of taxol. Further investigation in bioreactor showed that noly 1.5 mg/L taxol was produced when DO(dissolved oxygen) level was 20%. Taxol production increased when DO level was increased to 40%-60%. Moreover, taxol accumulation was remarkably improved by the cultivation of cells initially at the DO level of 60% during the growth phase for 14 days followed by changing the DO level to 20%-40% during the taxol production phase for another 10 days. An optimum taxol level of 7.2 mg/L was obtained by the dissolved oxygen controlled process.