The unloading valve is selected as the key part of pressure control and overload protection system in the emulsion pump station (EPS). However, severe cavitation erosion occurs on the inner wall of the valve sleeve located in a downstream outlet, which leads to the performance deterioration, instability, and even failure of the unloading valve. This paper aims to reduce the cavitation phenomenon by optimizing the structure of the spool and improving the streamline direction of the unloading valve. The change in internal structure can reduce cavitation cloud formation along with the internal mechanism of the valve. The working conditions of its flow versus time-dependent data’s are obtained by AMESim, and considered as the boundary condition in Fluent. In addition, the changes in flow behavior and input data’s are analyze and validate before the structural is optimized. After an analysis, the variations in velocities and vapor phase, indicating the higher in pressure drop at its minimum size of valve opening and further consideration for design and development stages. Two innovative structures of valve throttling spool are proposed as a simplified design stage and then carefully curved based on internal geometry to uniformly distribute the velocity vector and streamlines. Subsequently, the post-CFD results reveal the presence of factors affecting properties such as pressure loss, high velocity in the outlets, and concentrated of the vapor volume fraction are decreased under the modified throttling structure and effectively lowers the intensity of cavitation phenomenon.