Abstract: Level of organic matter often serves as the first indication of a fertile soil, and soil organic carbon is the important role in the study of global change. In order to provide a scientific basis for accurate calculation of soil organic matter and organic carbon and rational fertilization, the study took 14 samples in newly reclaimed cropland of Ninghai County as an example, and compared calculation methods of organic matter content and organic carbon content of surface soils (0- 30 cm). The results showed that: levels of organic matter had declined by 22 percentage (mean from 23.1 to 18.0 g/kg) when the gravels (>2 mm) were included in these samples. While according to the calculation method of USDA and the evaluation criteria of Agriculture and Agri-food Canada, organic carbon content of surface soils (0-30 cm) belonged to the low levels (from 1.97 kg/m2 to 8.97 kg/m2).