By using an LKB-2277 Bioactivity Monitor and cycle-flow method, the thermogenic curves of aerobic growth for Bacillus thuringiensis cry II strain at 28 ℃ have been obtained. The metabolic thermogenic curves of Bt cry II contain two distinct parts: the first part reflects the changes of bacterial growth phase and the second part corre-sponds to sporulation phase. From these thermogenic curves in the absence or presence of Sm3+, Dy3+ ions, the thermokinetic parameters such as the growth rate constants k, the interval time t I, the maximum power PMAX1 and heat-output QLOG for log phase, the maximum power PMAX2 and heat-output QSTAT for stationary phase, the heat-output QSPOR for sporulation phase and total heat effects Q T were calculated. Sm3+ and Dy3+ ions have pro-moting action on the growth of Bt cry II in their lower concentration range, on the other hand, they have inhibitory action on the sporulation of Bt in their higher concentration range. It has also been found that the effects of Sm3+ and Dy3+ ions on Bt during the sporulation phase were far greater than those during the bacterial growth phase. It was concluded that the application of Bt for controlling insecticide could not be affected by the presence of the rare-earth elements in the environmental ecosystem. By using an LKB-2277 Bioactivity Monitor and cycle-flow method, the thermogenic curves of aerobic growth for Bacillus thuringiensis cry II strain at 28 ° C have been obtained. The metabolic thermogenic curves of Bt cry II contain two distinct parts: the first part reflects the changes of bacterial growth phase and the second part corre-sponds to sporulation phase. From these thermogenic curves in the absence or presence of Sm3 +, Dy3 + ions, the thermokinetic parameters such as the growth rate constants k, the interval time t I, the maximum power PMAX1 and heat-output QLOG for log phase, the maximum power PMAX2 and heat-output QSTAT for stationary phase, the heat-output QSPOR for sporulation phase and total heat effects QT were calculated. Sm3 + and Dy3 + ions have pro-moting action on the growth of Bt cry II in their lower concentration range, on the other hand, they have inhibitory action on the sporulation of Bt in their higher concentration range. It has also been found that the effec ts of Sm3 + and Dy3 + ions on Bt during the sporulation phase were far greater than those during the bacterial growth phase. It was concluded that the application of Bt for controlling insecticide could not be affected by the presence of the rare-earth elements in the environmental ecosystem.