Abstract: Jet scouring has been widely used and played an important role in dredging engineering, so it is necessary to further study the jet scouring. Based on Eulerian model and k-ε turbulence model, the numerical simulation of scouring on sand bed with the particle size from 0.04mm to 0.23mm by 2D vertical submerged jet is conducted to study the influence of particle size and jet velocity on sand bed scouring. The result show that in the given range of particle size and velocity, the maximum scour depth and the volume of suspended sand are positively correlated to the jet velocity and negatively correlated to the particle size, and the influence of the jet velocity is greater.