The Asymptotic Waveform Evaluation (AWE) technique combined with the Method of Moments (MoM) is often applied to accelerate the calculation of the wide-band Radar Cross Section (RCS) of the target. However, when the object is electrically large, the method is still quite time-consuming. Hence, in this paper, a new type of Krylov subspace iterative methods based on flexible inner-outer iterative ... [Show full abstract] technique is adopted to solve the large dense matrix equation arising from the discretization of the Electric Field Integral Equation (EFIE). Near-field matrix preconditioning technique combined with the dual threshold incomplete LU factorization preconditioning technique will be applied to the reduction of the iterative number of FBICGSTAB. The numerical results show that the computational efficiency of the wide-band RCS for electrically large objects is improved significantly by using the method presented in this paper without sacrificing much accuracy.