Objective:To compare the bioactivities of Taohua anti-diarrhea granula prepared by two different methods based on biothermo-kinetics study.Methods:The coarse and fine powder preparations of Taohua decoction were prepared.Microcalorimetry was used to obtain the metabolic curves and biothermo-kinetic parameters of Escherichia coli(E.coli) growth after treated by the two preparations to evaluate their bioactivities.Results:The values of growth rate constant k and maximum heat-out power Pm declined with the concentration increase of the 2 preparations; meanwhile,the values of peak time of the highest peak tm and growth inhibitory ratio I increased with the concentration increase of the two preparations.The results showed that the growth of E.coli was inhibited and the inhibitory effect was strengthened with the concentration increase of the two preparations.The IC50 was 35.9 mg/ml for the coarse powder preparation and 31.4 mg/ml for the fine powder preparation.Aggregate analysis of the metabolic curves and biothermo-kinetic parameters of E.coli indicated that the fine powder preparation of Taohua decoction had stronger inhibitory action against E.coli growth than the traditional coarse powder preparation.Conclusion:Microcalorimetry can be used to examine the bioactivity differences of the fine and coarse preparations of Taohua decoction.Superfine comminution may increase the inhibitory action of Taohua decoction.