Abstract: The vibration issue due to pipe orifice cavitation of NPP containment spray system（EAS） is analyzed combining the field vibration test and numerical simulation analysis method. The study finds that pipe orifice plate choking leads to the emergence of cavitation downstream of the orifice plate, which resulting in the pipeline vibration. The optimization design of the pressure drop, number of stages, aperture and structure of the orifice is conducted by numerical calculation. The scheme of reducing the cavitation using the three-stage orifice is presented and the integrity evaluation of the scheme is carried out. Through the re-appraisal of the modified pipeline, it is shown that the engineering design scheme based on the optimal design and analysis method can solve the problem of strong vibration of piping induced by cavitation, and greatly reduce the vibration and noise of pipeline, and the pipeline system can be safely operated in long term.