For orthogonal frequency-division multiplexing (OFDM) system, the length of cyclic prefix (CP) is selected on the basis of the expected maximum delay spread. When the CP length is shorter than the maximum delay spread, inter-symbol interference (ISI) and inter-carrier interference (ICI) will occur. By means of conventional one-tap frequency domain equalization (FDE), the desired symbols can not be recovered. In this paper, a soft-decision-directed one-tap turbo FDE technique is proposed for OFDM system without CP. After tail cancellation, the proposed algorithm performs soft cyclic reconstruction and one tap minimum mean-square error (MMSE) FDE iteratively to minimize the performance degradation. Simulation results show that, compared with existing methods, our proposed algorithm can achieve better performance.