Analysis of the regional changes of soil organic matter (SOM) and its relationship with pH and bulk density (BD) in agricultural areas of China were conducted. That would provide support for improvement of cultivated land fertility and soil structure. The characteristic of SOM changes were analyzed based on 913 national long-term monitoring sites which were carried out in 7 regions (Northeast, NE; North China, NC; Northwest, NW; Middle of Yangtze River, MYR; Yangtze River Delta, YRD; South China, SC; and Southwest, SW). Soil pH and bulk density were also evaluated. The results showed that the averaged SOM content in the agricultural cultivation areas were between 22.4 and 24.8 g/kg., and 72.5% of total monitoring sites were with SOM content grade <30.0 g/kg (grade 3~6). There were significantly difference of SOM content in soil cultivated layer among regions (p<0.05). Soil organic matter content in MYR was significantly higher than that in other regions. Soil pH and BD in the agricultural cultivation areas were (6.90±1.20), and (1.30±0.15) g/cm³. Soil utilization patterns affected SOM content, pH, and BD. The SOM content in paddy fields were significantly higher than that in upland. The pH and BD in upland were significantly higher than that in paddy fields. The Adams equation and exponential equation were recommended to fit response relationship between BD and SOM (R²=0.09, RMSE=0.17, n=759), pH and SOM (R²=0.16, RMSE=1.24, n=886).The SOM content was generally low in plowed layer in the agricultural areas, and that showing a decreasing trend from southeast to northwest of China. Soil pH and BD showed significant negative correlation with SOM. The Adams and exponential equation could well fit the responses relationship between soil BD and pH to SOM, and that could be used for nonlinear interpolation to supplement BD and pH missing values.