In this study, a tensor train-based tensor completion scheme is proposed to reduce the setup time of fast Fourier transform (FFT) - accelerated integral equation (IE) simulators. The proposed scheme is applied to completion of the system tensors arising in FFT-accelerated IE simulators developed for the analyses from DC to high-frequencies. The preliminary results show that the scheme yields 10.8x, 3x, and 2.6x computational time-saving during the generation of system tensors with 10 −4 accuracy for electrostatic, quasi-magnetostatic, and full-wave analyses, respectively.