The unstable hydrodynamic forces caused by slug flow make the vibration of the riser more complex. The gas-liquid changes were tracked based on the VOF(volume of fluid) multiphase flow model, and the vibration responses of the Lazy-wave risers with slug flow were obtained through the single fluid-solid coupling method. The influence of the changes in the gas-liquid ratio caused was explored by the superficial liquid velocity on the vibration responses at the high-curvature positions of the riser. Through the analysis in the time domain and frequency domain, it is found that: as the gas-liquid ratio increases, the in-line and vertical displacements of the riser first increase and then decrease, exhibiting standing-wave characteristics, while the cross-flow displacement first decreases and then increases, and the phase differences among the measuring points reflect the traveling-wave characteristics. In terms of frequency, in the cross-flow direction, the dominant vibration frequencies at different measuring points are different. As the gas-liquid ratio increases, the difference in the contribution of the first-order and second-order frequencies to the displacement decreases, and the modal competition intensifies. The research results provide references for the study of riser flow-induced vibration.