In order to study the influence of periodic wave impact on fluidsolid coupling vibration of deep sea liquid pipelines, Finite Element Analysis (FEA) method is used to simulate and analyze the vibration characteristics of the branches of Ytube pipeline system under the separate action of internal and external fluids and the combined action. The results show that: The periodic impact load of wave aggravates the pressure fluctuation of the fluid in the pipeline system, the maximum displacement of the vibration of the pipeline system and the maximum equivalent stress of the pipeline system are increased. As the fluctuation of internal fluid pressure increased, the maximum displacement of the vibration of the pipeline system and the maximum equivalent stress of the pipeline system both decrease to a certain value before increasing. The impact frequency of the wave, the fluctuation of internal fluid pressure, and the maximum displacement of the vibration of the pipeline system are all in direct proportion.