In this study we investigated the effects of carbon and nitrogen sources, and the carbon to nitrogen ratio (C:N) of growth medium on the production of plasmid DNA by $pUK21CMV{eta}1.2$ harbouring recombinant E. coli. The results indicated that sucrose and casein peptone were the most suitable carbon and nitrogen sources, respectively, for plasmid production, and the plasmid concentration was significantly influenced by the C:N ratio. A Box-Behnken design and surface response methodology were employed to formulate the optimal medium. In the optimized medium, a plasmid concentration of 51.80mg/L and a plasmid selectivity of 23.49mg/g were achieved after 24h of incubation. These values were approximately 3.5 and 1.7 times higher, respectively, than those obtained on the original LB medium.