Abstract: Due to the band-limited underwater acoustic(UWA) channels, it is a good way to make use of band-width-efficient modulation techniques for high-speed communication.Orthogonal Frequency Division Multiplexing(OFDM) modulation, in which the overlap of subcarriers is allowed, has very good application prospect.But demodu-lation of OFDM is very sensitive to frequency offset and synchronization;the former is often severe in UWA commu-nication because of Doppler phenomenon.Employing hyperbolic frequency modulation signal as a pilot makes it possible to calculate the frequency offset accurately and achieve synchronization.