Abstract: The window spallation target is the only high power liquid metal spallation target demonstrated through experiments and measurements, which is the crucial part of Accelerator Driven Sub-critical System (ADS). It is important to study the flow of working fluid inside the spallation target for optimizing the spallation target design. The detailed study for the flow field of the target was carried out by visualization experiment and numerical simulation. The water was used as the working fluid in the experiment. The particle image velocimetry (PIV) was applied for visualization of flow field. The computational fluid dynamics analysis was performed by using FLUENT. Five turbulent models, standard k-ε, RNG k-ε, Real k-ε, SST k-ω, and RSM models, were utilized to calculate the flow at different velocities. The calculated results were given and compared with the experimental data. It is shown that RNG k-ε model with the corresponding wall functions can accurately simulate the flow of the window spallation target.