In view of the problems such as obvious soil disturbance, undulation of seeding depth and poor moisture retention capacity of furrow when no-tillage seeder is applied to reseeding of degraded grassland, a multifunctional furrow opening device is designed, which integrates functions of cutting roots, opening furrows and returning soil. A flat disc is used to break the soil and cut the roots. Then an inverted T-furrow opener is applied to form a stable furrow and clean the roots around the seeds. In the final stage, the soil-returning mechanism is applied to bury the seeds with the soil that has been squeezed out of the ground during the furrow opening process. The discrete element method was used to assist the design of the multifunctional furrow opening device. Hertz-Mindlin with JKR contact model was applied to create a discrete element soil model. The results of discrete element method simulation showed that the best operation effect of inverted T-furrow opener was achieved when the connecting shank was vertical. Analyzing the force of the soil-returning mechanism, the stiffness coefficient of the spring was determined to be 0.6 N/mm, and the initial pressure of the spring was determined to be 60 N. Field experiment and discrete element simulation test were carried out to verify the operation effect of the multifunctional integrated trenching device. The test results show that the optimal operating speed range of the device is 0.8-1.2 m/s. The soil disturbance was small and the side ridge width was not more than 50 mm. The grooving depth is stable and controllable, and the fluctuation of the grooving depth does not exceed 5 mm. The operation effect of soil return mechanism is good, which is helpful to improve the soil moisture retention ability of planting ditch.