Aiming at the problem of cutting hard clay for submerged high pressure water jet,based on the coupled Eulerian-Lagrangian method,the law of velocity decay of the jet through the submerged water is introduced,and a finite element model is established to analyze the cutting effect,which is finally verified by laboratory test.The method combines the advantages of Euler algorithm and Lagrange algorithm,and is suitable for the analysis and calculation of fluid-solid coupling between jet and soil.The water body adopts the Euler algorithm,and the soil body adopts the Lagrange algorithm.The contact surface of soil and water can be accurately captured.The numerical results show that under the action of high pressure jet,the cutting depth of hard clay decreases with the increase of cutting speed and increases with the increase of jet pressure.Compared with the experimental results quantitatively,the results agree well with each other.The model can well simulate the cutting behavior of high-pressure jet on hard clay under submerged condition,which provides a new research idea for this problem.