Abstract: This study proposes a finite element model for submerged water jet excavation using a cylindrical nozzle with an aim to determine the depth and diameter of jet orifices during water jet excavation. The model's accuracy was verified through indoor experiments, employing the Lagrangian-Eulerian fluid-solid coupling algorithm. The response surface method was utilized to establish a predictive model for the depth and diameter of jet orifices, which includes the impact of nozzle diameter, jet standoff distance, jet pressure, and their interactions. The construction parameters for jet excavation were optimized using a satisfaction function. Results indicated that for excavation depths of 10 cm, 15 cm, and 20 cm, keeping the stability of the jet orifices to the maximum required higher jet pressure(7.2 MPa), smaller jet standoff distance(1 cm), and an appropriate nozzle diameter(0.928 mm, 1.164 mm, and 1.345 mm). After optimization, the predicted values of jet orifice depth and diameter for the specific target excavation depths showed an error of less than 15 % compared to the experimental values, demonstrating the credibility and reliability of the predictions.