Abstract: To analyze the whole process of sluice downstream sediment scouring due to horizontal jet, the downstream scouring process of a fixed floor were simulated by using sediment scour model, RNG k-ε model and FAVOR method in Flow-3D software and on the basis of the hydraulic model test. The test simulation calculation was carried out according to the conditions of original hydraulic model. Combining with the result of hydraulic model tests, the water surface profile, velocity distribution, scouring hole depth and dune height during the scouring process were compared and analyzed. The result shows that the water surface profile and velocity distribution of the model test and simulation is consistent well, also the simulated scouring hole depth and dune height are in good agreement with the test. The sediment motion is analyzed, and the scouring process in case of different sediment grain size is simulated and the results are compared. It is concluded that the maximum scour depth and dune height decreases with increase of particle size when the scouring reaches the equilibrium, which is consistent with the theoretical analysis. It is proved that the sediment scouring model can be used in the analysis of variables in hydraulic tests.