Abstract: The inter-symbol interference caused by multi-channel propagation is the key factor affecting the performance of underwater acoustic communication system. Single-carrier frequency domain equalization (SC-FDE) technique based on orthogonal frequency division multiplexing (OFDM) can effectively combat the multi-channel interference in underwater acoustic channel, while avoiding the high peak to average power ratio of the OFDM technology. In this paper, the decision feedback equalization algorithm is first introduced and compared with the other two equalization algorithms, and then, in order to improve the reliability of SC-FDE system and the effective utilization of system bandwidth, the traditional data frame structure is improved. The unique words (UW) are divided to improve the accuracy of channel estimation, thereby reducing the bit error rate, increasing the reliability of transmission; In order to improve the bandwidth utilization rate, the number of useful symbols in the data frame is increased when the UW sequence length is constant, and the system error performance is almost unchanged. Finally, the pool test is carried out to verify the effectiveness and reliability of the algorithm.