Based on field investigations of Honghuaerji,the native habitat of Pinus sylvestris var.mongolica,it was found that in the forest soil organic Carbon,and total Nitrogen were significantly correlated with and soil texture.,especially with silt content,showing a correlation coefficient being as high as 0.7028 and 0.7209,respectively,but negatively with bulk density,being 0.5760 and 0.5937,respectively in correlation coefficient.In comparison with the forestland under white birch and farmland,the forestland under Pinus sylvestris var.mongolica was relatively lower in content of SOC and TN,being 19.5kg/m² and 1.8kg/m² respectively.At the same time,SOC and TN in the forestland under Pinus sylvestris var.mongolica were also found related to topography.Generally,they were higher in the soil on the sunny slope than in the shady slope and in the down slope than in the upper slope.Besides,they were increasing with age of the forest and rising to the peak when the forest was 25 years old,and then showed a decreasing trend after it was 30 years old,which was closely related to change in soil texture.So was the difference in SOC and TN contents between soils under different plant communities.