Effects of the subgrid length-scale in the Delayed-Detached Eddy Simulation(DDES) are investigated based on the Spalart-Allmaras(S-A) and the k-ω Shear Stress Transport(SST) turbulence models. Driver & Seegmiller"s experimental results are used to validate numerical results. Grid convergence with grid resolution and subgrid length-scale is investigated. The simulation results show that the volume method for the subgrid length-scale is more resistant to unfavorable effects of the grid size in the periodic direction than the maximum method. Using a sufficient grid resolution and an appropriate subgrid length-scale, both S-A based DDES and SST based DDES methods can provide a good correlation with the experimental data.