The growth and metabolism ability of two strains of petroleum microbe isolated from oil reservoirs was studied by calorimetry. Thermal power-time curves under various environmental conditions (including temperature, acidity, salinity and carbon source) were determined. Typical microbial growth thermal power-time curves were obtained. By fitting the curves mathematically with the 'three-point method' under an inhibitory condition, the growth rate constants and the optimum growth conditions (including temperature, acidity and salinity) of the microbes studied were obtained. Irregular thermal power-time curves were obtained when the petroleum microbe E grew in the media containing different carbon sources.