Abstract: In the field of offshore oil and gas development, the pipeline transmission pressure and flow velocity increase, and the vibration caused by the internal flow of a pipeline becomes one of the important items for flow safety guarantee. Herein, the flow-induced force caused by the gas-liquid two-phase flow was studied by constructing an integrated experimental platform of riser. Then, the local flow pattern in the riser was divided according to the signal of liquid holdup and the observation results of the experiment, and the factors affecting the flow-induced force were analyzed. Additionally, the computing model of the main fluctuation frequency and the maximum root-mean-square value F_rms of flow-induced force was established. The results show that: F_rms appears at the boundary between the slug flow and the churn flow, and with the increase of air voids at the ingress, F_rms is basically in the trend of increasing at first and then decreasing. However, for the SS Ⅱ type severe slug flow, large flow-induced force can still be produced. The research results can provide a theoretical reference for the design and operation of marine riser system.