Abstract: Time-varying multipath underwater acoustic channel is an important influence factor for underwater acoustic communication system. It is of great significance to understand the characteristics of underwater acoustic channel and to model the underwater acoustic channel. First, the existing shallow water time-varying channel model was analyzed,and then from perspective of time domain, the small scale parameter of the channel is modified by AR(p) model. The characteristics of amplitude, delay, time coherence coefficient and system function of each path were analyzed using the real collected data from Lianhua Lake in Heilongjiang, China. The simulation results shows that the modified model has a good agreement with the experimental results. The characteristics of underwater acoustic channel were analyzed from many aspects which can help to understand the underwater acoustic channel, and provide a simulation channel model for the performance evaluation of underwater acoustic communication system.