Abstract: Soil organic matter(SOM) content and stability are important parameters for soil quality. There is a need to determine SOM content and stability with easy and cost-effectively techniques. This study aimed to evaluate the applicability of thermal analysis for determining SOM content and stability. Soil samples were collected from a long-term paddy fertilization experiment located in Ningxiang County of Hunan Province. The study consisted of 5 treatments: no fertilizer application(CK), chemical fertilizer(CF), straw amendments and chemical fertilizer(RCF), 30% organic fertilizer and chemical fertilizer(LMCF), and 60% organic fertilizer and chemical fertilizer(hMCF), which created a gradient of SOM content and stability. Four aggregate fractions(>2, >0.25-2, >0.05-0.25, and ≤0.05 mm) were obtained by using the wet-sieving method. Thermogravimetry(TG) and differential scanning calorimetry(DSC) analyses were conducted on SOM content and stability of bulk soil and aggregates samples from room temperature to 700 and 500 ℃, respectively. Firstly, there were 2 groups of SOMs in the soil: the thermal-unstable SOMs that decomposed in the temperature range of 200-350 ℃, and the thermal-stable SOMs that decomposed in the temperature range of 350-550 ℃. Secondly, SOM content determined by thermal analysis was in the range of 4%-8%, SOM content determined by elemental analysis was in the range of 3%-6%. Comparing to SOM data from elemental analysis, the thermal analysis method overestimated SOM content by 2.10 percentage points. There was a positive linear relationship between SOM contents between the 2 methods(r=0.88，P=0), thus thermal analysis values could be converted to conventional ones by subtracting 2.10% from the readings. Thirdly, the proportion of thermal labile SOM in total SOM(Exo1/Exot) and the temperature at which half of total SOM decomposed(TG-T₅₀) were used to indicate SOM thermal stability. ParameterExo1/Exot correlated positively to TG-T₅₀(r=-0.95，P=0) and was more sensitive to SOM thermal stability than did TG-T₅₀, thus Exo1/Exot was a more reasonable parameter to indicate SOM thermal stability. Fourthly, Exo1/Exot showed positive correlation with the Fourier transform infrared spectroscopy absorbance of carbohydrates, alkanes, aromatic series, and soil basal respiration and metabolic quotients, indicating that the thermal stability of SOM had a good consistency with chemical and biological stability. Fifthly, integrated application of organic and chemical fertilizers increased SOM in aggregates significantly. A combination of crop residue and chemical fertilizer was also beneficial to SOM improvement. No apparent effect was observed on plots with chemical fertilizer alone. In terms of SOM content, the largest value appeared in the >0.25-2 mm fractions, followed by the >2 and ≤0.05 mm fraction. Finally, SOM thermal stability under the treatments with high manure and rice residue tended to be higher than under the treatments of chemical fertilizer alone and control. There was no homogeneous response in SOM thermal stability to aggregates size and bulk soil under different fertilizer treatments. Comparing to traditional chemical oxidative technique and elemental analysis method, thermal analysis has the advantages of simple, quick, no requirement of sample pretreatment, and providing both SOM content and stability. Therefore, we concluded that thermal analysis was a viable technique for measuring SOM content and thermal stability, and can be applied for studying management effects on SOM content and stability, and for evaluating soil quality.