With the development of the deepsea strategy, the offshore oil and gas exploitation towards to deep sea, and more and more offshore risers are put into use in ocean engineering. Due to the variable flow rate and seabed terrain, the slug flow is typically encountered in flexible risers. Slug flow characterized by the obvious period usually contributes to the unstable fluid forces acting on the pipe wall and hence the dynamic response, causing the fatigue failure of flexible riser. The experiments of slug flow-induced vibration are performed in an air-water loop. The synchronous monitoring of vibration response and flow regime are achieved using the non-intrusive highspeed cameras. The influence of mixture velocity and gasliquid ratio on flexible riser vibration is examined in terms of the tempospatial amplitude and frequency, liquid slug length, pressure fluctuation and the associated relationships among them. The results indicate that the amplitude is enlarged while the fundamental mode dominates the vibration response with increasing the gas-liquid mixture velocity at a fixed gas-liquid ratio. Although the variation of liquid slug length is not pronounced, the pressure fluctuation becomes more violent. The amplitude is increased and the length of gas plug and liquid slug are prolonged as the gasliquid ratio increases at a fixed mixture velocity. In addition, the pressure fluctuation is also enhanced though the average pressure is decreased.