The analysis of a single-phase flow field inside a cyclone separator has been performed using large-eddy simulation (LES) using Lattice-Boltzmann method based CFD code XFlow. The simulations are performed over the uniform grids with a total of 1.05 million cubic cells. Based on the inlet velocity and main body diameter, the Reynolds number (Re) amounts 14,000. To model the effects of small scales and to account for the near-wall damping, wall-adapting local eddy-viscosity (WALE) model is used. The Spatio-temporal behavior of the large coherent structure ‒ especially the one in the core region ‒ is also very well captured. LES elucidates a good agreement of the mean as well as fluctuating (expressed as the root-mean-square error values) components of velocity with the measured values. The non-dimensional frequency estimated by LES ‒ based on the fluctuating axial velocity, tangential velocity, and static pressure values ‒ agrees well to the experimental value.