Abstract: Tillage erosion is a new field of soil erosion research. To quantitatively describe processes of tillage erosion in loess region of China, this paper modeled the tillage erosion here by conducting tillage experiment, in which small cubes were used as the tracers to trace and monitor soil movement, and regressive and theoretical analyses, and developed the model of tillage erosion with which net erosion modulus at any point of slope profile can directly be calculated. The results showed that in the case of across slope tillage operation of come and go single pass along contour line from down slope to up slope in which the soil was turned down slope with local traditional plow pulled by animal power: (1) Mean horizontal distance of soil displacement per tillage operation in slope aspect direction is linearly related to slope gradient; (2) The net erosion modulus at any position of slope profile per tillage operation is affected by soil bulk density, tillage depth, coefficient determined with soil and tillage conditions, and topography curvature.