Soil organic carbon equilibrium (SOCE) is a complex process determined by the interactions between of different latent variables, or between measurable variables, and between the latent and measurable variables. The interaction relationships could be well expressed by the structural equation modeling (SEM). Based on the surface soil (0-20 cm)data of some typical counties (Dunhua, Yushu, Gongzhuling, Changtu and Fuxin) in the Northeast China, a SEM of soil organic carbon equilibrium in those counties was simulated, and the relationships of SOCE as affected by different variables were evaluated. The results indicated that there were significant interactions between latent variables (climate regimes, soil properties and management practices). Soil properties had a direct positive effect on SOCE with a path coefficient 1.01, while climate regimes and management practices influenced on SOCE indirectly through soil properties. Moreover, the influence of climate was greater than that of the management with path coefficients of 1 and 0.87, respectively. According to the path coefficients calculated by the SEM on SOCE, it is very important to pay more attention to the effect of human activities (especially tillage practices), on the process of SOCE and it is extremely crucial to optimize SOCE by a better development.