Abstract: To better predict the flow-accelerated corrosion (FAC) in power plant pipelines, the physical parameters of the steam-water mixture were calculated based on the gas holdup according to the actual operating conditions of the power plant pipeline. Using COMSOL software, the flow field downstream of the orifice plate in the pipeline was simulated, and the concentration of iron ions and the distribution of turbulent kinetic energy were analyzed. The variation patterns of velocity, wall shear force, and mass transfer coefficient under different flow phases were obtained. Combined with single-phase flow and two-phase flow accelerated corrosion prediction models, the impact of gas holdup on flow-accelerated corrosion was analyzed. Results show that the presence of water vapor leads to an increase in the FAC rate of two-phase flow on the upper, middle, and lower walls of the pipeline downstream of the orifice plate, compared to the FAC rate of single-phase flow, with the most significant increase occurring on the upper wall. When the temperature is 150 ℃, the medium is two-phase mixture, and the gas holdup is 0.5%, the FAC rate at the wall is the highest, being 1.001 112 times that of the single-phase flow case.