High turbulent swirling reacting flow is investigated in a swirled premixed burner using hybrid RANS-LES method. The hybrid method is the Detached Eddy Simulation (DES) and it is combined with the Finite-Rate/Eddy Dissipation (FR/EDM) combustion model to treat turbulence-chemistry interaction. The instantaneous flow fields are well captured by DES and the premixed flame is well reproduced by FR/EDM. It is shown that DES is capable to reproduce the experimental profiles of the mean axial velocity and temperature. Phase-angle analysis of the instantaneous flow field shows the presence of large-scale coherent structures. Q-criterion is used to visualize the 3D behaviour of the structures; it is found that the unsteady flow contains a Precessing Vortex Core (PVC) and Secondary Outer Vortex (SOV).