Abstract Adaptive equalization is an effective way to cope with intersymbol interference caused by multipath propagation in underwater acoustic coherent communication. An experiment is carried out to verify the coherent underwater acoustic communication technique and to study the performance of adaptive equalization algorithm promoted by the author. Data processing results show that there is poor performance at Ts/2 fractionally spaced equalization and by using Ts/4 spaced equalization the data is without error. This algorithm has better performance compared with conventional equalization algorithms because it has robust convergence performance for its adaptive stepsize behavior and has low computational load.