Water jacket plays an important role in ultrasonic water spray penetration detection.In order to design a water jacket with good coupling effect and to reduce the influence of water flow turbulence on acoustic coupling，this paper constructs a finite element simulation of geometric model，physical model，and numerical solution for the probe jacket to conduct fluid dynamics simulation.The simulation results show that without a rectification device，the water injected from the inlet collides with the inner wall of the probe sleeve，causing severe turbulence.After entering the outlet pipe，the turbulent state is still maintained，and the direction of the water flow line is chaotic.After adding a rectification device，the turbulence inside the probe sleeve is well suppressed，making the direction of the water flow into the outlet pipe conforming to consistency.This phenomenon becomes more pronounced as the number rectifying element increase.This article aims to simulate the state of the water column after the water flow passes through the outlet， especially after increase of initial water flow velocity. The use of FEM’s muti_physical field simulation function with addition of sound fields has laid the foundation for simulating changes in sound fields under turbulent conditions.