Adenylate cyclase (EC 4.6.1.1) catalyzes the formation of cyclic adenosine-3′,5′-monophosphate (cAMP) from adenosine 5′-triphosphate (ATP). Recombinant Escherichia coli overexpressing adenylate cyclase was used to synthesize cAMP by whole cell catalysis. Some key parameters were examined during the catalytic process, while pH and Mg2+ were found to influence cAMP production significantly. Optimum conditions were pH 8.52 and 30 °C with 77.2 mM Mg2+ in 100 mM Tris-HCl buffer, including 0.25% Triton-X 100 as detergent and 30 mM pyruvate sodium as enzyme activator for 6 h. 14.93 g/L of cAMP was produced with a conversion rate of 91.5%. The current work provided a potential way for the industrial production of cAMP.