Caloric value of humic acid in different soils determined through oxygen-bomb calorimeter method showed that the humic acid in different soils has different energe tic states and the total energetic state of soil humic acid was positively correlated with the soil organic matter,total nitrogen and the amount of soil humic acid.The humic acid pyrolytic properties observed by means of DTA and TG methods in different soils indicated that the humic acid from different soils showed similar heat effect peak and weight loss peak in DTA and DTG curves.Difference was found in its homologous enthalpy change (△H),the percentage of weight loss (W%),the maximum rate of weight loss (dW/dT) m,activation energy (E),and the specific rate constant(K₀).