In this study, a grassland root cutter based on abrasive air jet technology was designed to solve the problems of high soil disturbance and short tool life of traditional passive and active root cutters. This equipment innovatively uses high-pressure gas mixed with fly ash abrasive to form a high-speed jet to cut the soil and root system, and dynamically adjusts the depth of cut (50 ~ 150 mm) to realize the precise operation with low disturbance of the slit width of ≤ 10 mm. By simulating and analyzing the jet characteristics of the four nozzle structures, it is found that the cone-straight conical nozzle design significantly improves the clustering of the jet, the particle trajectory is more centralized and the cutting efficiency is optimized. A discrete element model was established based on soil measurement data, and the coupled soil-jet simulation showed that the depth of the slit reached 77.15 mm and the width was 6.02 mm under 5 MPa jet pressure, and that the depth increased to 143.52 mm and the width increased to 6.43 mm after raising the pressure to 20 MPa, which meets the agronomic requirements of breaking the soil and cutting the roots in degraded grassland. The study verified the feasibility of abrasive air jet technology in reducing operation cost and soil disturbance, and provided efficient equipment support for grassland ecological restoration.