CoQ10 is used not only as a medicine but also as a food supplement due to its various physiological activities. The production of CoQ10 by microbes is a successful approach for generating large amounts of this natural product. The effects of dissolved oxygen (DO) contents and the two-stage fermentation process on cell growth and CoQ10 production by Rhodopseudomonas palustris J001 were investigated. The optimal DO contents for cell growth and CoQ10 production were 45% and 15%, respectively. A two-stage fermentation process, which consists of a 1st stage with 45% DO, a 2nd stage with 15% DO and a synchronous feeding of 2.0% NaAc at the switching time (42 h after inoculation), has proven to be the optimum fermentation process for the production of CoQ10. The maximum biomass, CoQ10 production and CoQ10 production rate were 1.31 g l-1, 89.1 mg l-1, and 1.142 mg l-1 h-1, respectively, increased by 28%, 585% and 426% as compared to the one-stage batch production with 45% DO. The DO level was the major factor to increase the CoQ10 production by the two-stage process.