Abstract: The black soil region in Northeast China is China's vital commercial grain base. However, severe soil erosion on slope farmland poses a significant threat to this region's potential for grain production. The transition from traditional downslope ridging to contour ridging (briefly referred to as "contour ridging") is one of the primary measures for preventing soil erosion on slope farmland. By integrating high-precision Digital Elevation Models (DEMs) and designing standards, ArcMap can plan the orientation and position of contour ridges and estimate the reduction in soil erosion on slope farmland after contour ridging was implemented. Therefore, the degree of positional discrepancy between the designed and implemented contour ridges directly affects the effectiveness of contour ridging and the precision in evaluating its impacts and benefits. This study aims to assess the position accuracy of contour ridges designed by ArcMap using high-precision DEMs obtained from unmanned aerial vehicles (UAV). For this purpose, three fields where contour ridging had already been implemented were selected in the Sanjiang Plain of Heilongjiang Province, China. CORS RTK was used to precisely measure the XYZ coordinates of verification points along implemented ridges. Those measured point coordinates were compared with the designed ridgeline positions to analyze the positional discrepancies between the designed and implemented ridgelines. The results indicated that: (1) The average slope gradient along the contour ridgelines measured in the field (0.5° - 0.6°) was relatively close to that along the ridgelines designed using ArcMap (0.6°), and the elevation changes along most of the contour ridgelines showed a pattern of being higher in the middle and lower on both sides. (2) The positional offset between most of the measured and designed ridgelines was less than the width of a single ridge (1.3 m), and the median offset was one-third of the width of a single ridge. (3) The positional offset caused by the movement of ridging machinery could be greater than the offset resulting from the baseline setup, and measured points with larger positional offsets were often located at the edges of the plots as well as turns of the ridgelines. Therefore, during the designing ridgelines process, the turns should be made as smooth as possible. During ridging, reducing the speed at these turns to minimize errors and maintain the accuracy of the ridging path was recommended.