Abstract: To deal with 3D scattering problems, this paper applies multilevel inverse-based ILU (MIB-ILU) preconditioning to rapidly find the solution of the matrix equations in the finite element time domain method (TDFEM). The CPU time required by each updating step in TDFEM is greatly reduced by this preconditioning approach. The 3D scattering model and formulation of TDFEM was given. Then, the coefficient matrix was analyzed and the method using preconditioning approach was presented. Moreover, several numerical experiments were performed. The results demonstrate that the MIB-ILU approach exhibits high efficiency and significantly improves the computing capability of the TDFEM.