Abstract: In the report, the heat of hydration of potassium dichromate oxidation-colorimetric method was performed to determine the soil organic matter of the natural born mixed forest and farmland from the same altitude of Baodugu Nature Reserve. The results showed that there are obvious distribution differences of soil organic matter between the natural woodland and farmland. On the surface of natural forest, soil organic matter increased gradually, however, in the section, the distribution of soil organic matter of arable land is more uniform than that of farmland. SOM of natural forest soil is greater than that of cultivated land. SOM of the upper soil profile of two types of land was the highest, the maximum value often appears in the 0～10 cm layer, and then, decreases downwards. Our findings suggested that artificial reclamation had obvious effects on the content of soil organic matter, the cultivation for a long period result in the loss of soil nutrient, and the soil organic matter and total content is relatively low.