In order to clarify the characteristics of slope shape and slope changes in loess slope farmland under contour ploughing conditions, a simulated tillage experiment was conducted based on a combination of six slopes (3°, 5°, 10°, 15°, 20° and 25°) and five tillage intensities (6, 12, 18, 24 and 30 times). The influence of tillage intensity and slope gradient on the evolution characteristics of loess linear slope was discussed by using the needle method to measure the surface elevation before and after ploughing. The results showed that under the conditions of contour downward ploughing, the straight slopes with different slope gradients gradually evolved into "∽" type composite slopes with the increasing of tillage intensity. Under the same slope, with the increasing of tillage intensity, the slope toe extended, the projected slope length of the whole plot increased, the slope toe elevation increased significantly, the accumulation phenomenon was obvious, and the slope gradient decreased significantly. The elevation of the middle of the slope increased and gradually lifted the slope. The elevation and position of the new watershed formed at the top of the slope then decreased and moved downward, and the direct erosion rate gradually decreased and tended to be stable. The slope gradient controlled the distribution of soil during tillage by affecting the soil movement ability. Therefore, the greater the slope, the more obvious the change in slope shape after single tillage, and the greater the direct erosion rate. The results of the study were helpful for a deeper understanding of the impact of tillage erosion on the topography of slope farmland, and provide a theoretical basis for controlling soil erosion in slope farmland.