Abstract: A method for modeling of acousto-fluid interaction in water-jet ultrasonic testing is proposed to study the ultrasonic wave propagation characteristics in the water jet. The flow field of a water-jet probe is numerically calculated using computational fluid dynamics (CFD). The CFD results, including turbulent kinetic energy, flow velocity and pressure, are transferred to acoustic meshes as boundary conditions using weak formulations of the partial differential equations. The linear Navier-Stokes equations are used to solve for the acoustic changes caused by turbulent kinetic energy and flow velocity, thus modeling the acousto-fluid interaction in water-jet ultrasonic testing. Numerical calculations of the sound pressure distribution in the workpiece at different flow velocities are performed using the acousto-fluid interaction model. The results show that the sound field distribution is similar, but as the flow velocity increases, the pressure amplitude decreases. The echoes of the flat bottom hole are obtained using the proposed method and the echo amplitude decreases as the flow velocity increases. The accuracy of the proposed method is validated by comparison with experimental measurement results.