Abstract: The experimental study on gas-liquid two-phase flow in inclined pipe under fluctuant vibration condition was conducted. The vibration apparatus was combined with the two-phase flow experiment loop, the pipe inclination, vibration frequency and amplitude were changed, and the influence on flow pattern transition was analyzed. The study indicates that flow patterns under vibration condition are different from those under steady state condition, and two new flow patterns are found as the beaded flow and the fluctuant slug flow through flow pattern classification. The flow pattern transition diagrams show that the fluctuant slug flow zone expands with the increase of inclination while the other flow pattern zones are relatively reduced. The influences of vibration frequency and amplitude on flow pattern transition boundary are basically the same. The beaded flow and the proto slug flow zones expand with the increase of vibration frequency or vibration amplitude. Among the three variables, the vibration frequency has the greatest impact on flow pattern transition.