Abstract: In this paper, firstly, we have been studied the multiplication curves of E. coli at exponential phase of growth at 37 ℃ using microcalorimeter, LKB 2277 Bioactivity Monitor, and calculated the multiplication rate constant of E.coli using computer, which is k=0.0397±0.0025 min~(-1). Generation time, G=17.47 minutes, has been obtained from formula G=ln2/k, which is in close agreement with liter- ature value, G=17 minutes. Secondiy, using above method, rate constants of E. coli at different temperatures at exponential of growth have been determined. Finally, according to Arrhenius equation, the activation energy of E. coli multiplication has been obtained, which is 53.09 kJ mol~(-1).