Abstract: In order to solve the problem that there are a large number of high-pressure nozzles in the executive parts of the lotus root harvester in a large area of shallow water field, and the flow velocity difference between the nozzles is too large, which leads to the decline of the recovery efficiency of lotus root and the uneven quality of lotus root, this paper optimizes the executive parts of the lotus root harvester jet system. As an important component of the actuator, the stability of the jet has a great influence on the harvesting efficiency and scouring effect of lotus root. In order to reveal the influence of the connection process of the high pressure nozzle and the shape and diameter of the nozzle on the jet stability, based on the Edem-Fluent software, this paper carries out the environment modeling of the internal flow field and the coupling simulation of the nozzle of the executing part. It is found that by changing the shape of the nozzle to increase the chamfer and adjusting the diameter of each nozzle to the appropriate difference value, the stability of the nozzle is obviously improved. The standard deviation of the flow velocity fluctuation is changed from 0.164 m/s to 0.020 m/s. The average excavation depth is changed from 33.50 cm to 36.07cm, and the standard deviation of excavation depth is changed from 1.71 to 0.69.