Using vortex flowmeter is affordable, in addition, simple installation, high reliability, and high accuracy are some advantages of the vortex flowmeter. Vortex flowmeter works based on the vortex shedding principle, hence, the presence of particles in gas-solid flows may results in modulation in the turbulence intensity of the carrier phase and manipulate vortex shedding generated by a bluff body. In this study, the performance of the vortex flowmeter in the presence of particles with different sizes, density, solid volume fraction, and solid mass loading was studied with CFD simulation. The results indicated that the volume fraction and particles diameter are two significant parameters that affect vortex frequency. The vortex frequency is proportional to the velocity of gas flow and volume flow rate is calculated by Q= VA where V is average velocity in a pipe section with the area of A. Notwithstanding the neutral effect of microparticles on vortex frequency, moderate particles lessen the vortex frequency approximately by 20%. To coincide with the increase of solid volume fraction, the vortex frequency will descend, and in the high level of solid volume fraction, the vortex pattern goes to reach the instability. Since the size and volume fraction of the particles affects the frequency and consequently velocity, the gas flow rate measured by the vortex flowmeter is influenced by the presence of the particles. The numerical results have been validated with experimental data. The maximum relative error between the numerical simulation and the corresponding experimental data is 0.46% and 6.72 % for single-phase and gas-solid two-phase flows, respectively.