Abstract: The relations between the concentration of clay organic carbon and soil particle-size were studied in Pine forest and Maize field of different land-uses in the Jinzhou region of Dalian. Soil samples were collected according to profile layers, and soil organic carbon concentration, soil particle-size composition were measured and analyzed statistically. Results showed that vertical distribution of soil organic carbon content varies with soil depth and land use type, and the order of soil organic carbon mean concentrations were: Pine forest (7.619g/kg) > Maize field (5.971g/kg). The relation between the concentration of clay organic carbon and soil particle-size was highly significant (P<0.01). The correlation between the content of pine forest silt and the mean content of soil organic carbon was the biggest (R²=0.8822) so as to that of sand grain of maize field (R²=0.9786), while the correlation between the content of clay and the mean content of soil organic carbon both pine forest and maize field was the least (respectively=0.8186, 0.6145). The percentage of silt content was the highest(＞32%) in each soil layers. And the correlation with the content of silt was higher than that of clay, so the content of silt could be an important index of soil organic carbon so that use it to estimate the concentrations of soil organic carbon.