Two-phase flow measurement is a key issue in the natural gas industry. Among the many different flow meters available, the swirl meter stands out for its reliability, ease of maintenance, large measurement range, and strong output signal. In this study, computational fluid dynamics (CFD) simulations were conducted, using RNG k-e turbulence and Eulerian multiphase models, to investigate the gas-liquid two-phase flow characteristics in swirl meters. The CFD simulation results were then validated against the tested precession frequency of our experiment, and a satisfactory match was found between the outcomes. A detailed analysis was then conducted to generate profiles for velocity, pressure, etc. Based on examinations of the flow field distributions, it was found that gas flow inside swirl meters is sensitive to the presence of the liquid phase; the influence increased with the volume fraction of the liquid present. Further investigation indicated that the vortex precession was attenuated in the presence of the liquid phase. This led to the variation of the entire field; the pressure fluctuations at the end of the throat, in particular, resulted in metering errors of the gas flows.