Abstract: Numerical investigations were conducted on the vortex breakdown flows around an 80°/65° double delta wings using iDDES (improved-Delayed-Detached-Eddy-Simulation) based on k-ω-SST turbulence model. During vortex breakdown which occurs above the surface of the main wing as the incidence changed from 30° to 40°, flow information including aerodynamic force, pressure on surface and vortex structures was acquired and compared with experiment data adequately. The characteristics of flows during vortex breakdown were analyzed in great detail. Insight was concentrated on the patterns of vortex bursting, distributions of root-mean-square of pressure on the surface, unsteady aerodynamic force and fluctuation of pressure of representative samples. The relationships among the vortex bursting, power-spectral-density of unsteady aerodynamic and pressure samples, root-mean-square of pressure, spatial velocity and turbulent kinetic energy were revealed in depth. The correlations of different criterions about the location of vortex bursting point based on such flow information were depicted and assessed.