A fermentation process for production of super coiled plasmid DNA in E. coli for use as a DNA vaccine was developed. In the process a feed-back control nutrient feeding strategy based on pH and DO was used to regulate the cell growth rate by controlling the interactivity of the nutrient feed rate, pH and DO. The process increased the total yield of plasmid DNA by approximately 4 fold as compared to batch fermentation. The final cell yields of the process reached 56 gl?1 dry cell weights (OD550 nm 112) within 23 h. A plasmid DNA of 5.6 g l?1 was obtained by using an alkaline lyses method.