The construction of farmland conduit is a major part of irrigation facilities. Most farmland conduit is built by human and general excavator in China, the shape of conduit is not standard and the surface is very coarse. It is a main reason that a lot of water was wasted in the transportation process, so improving the quality of conduit construction has a significant role in achieving the target of agricultural water conservation. According to the status of special equipment for farmland conduit construction is exile, 1KY-40 hydraulic drive ditcher for farmland conduit was researched and designed in order to meet the needs of high quality farmland conduit construction. The ditcher is a tractive structure and its operating principle is that the symmetrical cutter is driven by an independent hydraulic power system so as to cut soil, the cutter can cut and throwing soil, the ditcher is dragged by tractor and the conduit with trapezoidal section can be excavated. The GPS automatic navigation system was integrated in the tractor, which can improve the trenching operations to improve linear precision of ditching. The test showed that the ditching depth of the ditcher was 407mm, the operating speed can be up to 0.12m/s, the stability of the ditching depth was 97.1%, the top width of conduit was 984mm and bottom width was 305mm, the linear deviation of ditching was less than 90mm when soil water content was 15.8% and soil compactbility was 0.31MPa under the condition of using the GPS automatic navigation system. The application experiments of 1KY-40 hydraulic drive ditcher for farmland were completed in Beijing, Jiangsu and Heilongjiang of China. The experimental results indicate that it can meet the construction of trapezoidal section conduit under the local soil conditions.