In order to solve the problem that the continuous pressure fluctuation of slug flow causes the vibration of lazy-wave riser, the single fluid-solid coupling method is used to study the vibration characteristics of lazy-wave riser under the action of internal slug flow. The results show that: the slug flow with a mixed flow velocity of 1.5 m/s and a gas-liquid ratio of 1 is of great influence on the amplitude of the riser, especially the amplitude of the cross-flow direction; in addition, the vibration frequency in the in-line direction decreases slightly, but the vibration frequency in the cross-flow direction increases significantly, which excites the higher-order modes and produces resonance. The results can provide reference for the study of the vibration characteristics of the lazy-wave riser.