Aiming at the current fixed scouring method of traditional hydraulic root digging nozzle, which has the problems of low operating efficiency and serious leakage, a reciprocating hydraulic scouring root digging device test platform was designed. Fluent simulation was used to carry out one-factor experiments on the shape of the nozzle, and the cone-column shape was found to be the optimal shape. Using Fluent-EDEM coupled simulation to carry out L9 (34) orthogonal tests on the key dimensions and working parameters of the nozzle, the optimal parameters of the nozzle are 15mm diameter of the outlet, 50mm height from the mud and 30° jet angle. The theoretical analysis of the nozzle trajectory and scouring area was carried out by using the integral method, and the theoretical optimal forward speed of the nozzle was 17.3mm/s and the swing speed was 130.7mm/s. Based on the test platform of reciprocating hydraulic scouring and root dredging device, a single nozzle scouring performance test was carried out, and the results verified the reliability of the nozzle key dimensions and working parameters of the simulation experiments. The results verify the reliability of the simulation experiment on the key dimensions and working parameters of the nozzle. In order to investigate the comprehensive influence of jet angle, forward speed and swing speed on lotus root surfacing rate, Box-Behnken centre combination performance test was carried out, and the results showed that the lotus root surfacing rate was the largest when the jet angle was 25.7°, the forward speed was 10.3mm/s, and the swing speed was 191.5mm/s, and the results of the simulation and the test platform were 94% and 92%, the results can provide reference for the research of lotus root harvesting machinery and hydraulic scouring principle.