Underwater communication is an important research of applied underwater acoustic since sound wave is the only effective way of transmitting messages under water. Underwater communication has always been a complicated problem especially in the shallow water environment due to the influence of multipath propagation. In the past, research on underwater communication had been done mostly by numerical simulation or laboratory experiments instead of doing in real oceanic areas. As a result, several research teams such as the Institute of Oceanography in Taiwan University, the Naval Research Laboratory and the acoustic laboratory of National Sun Yat-sen University Institute of Applied Marine Physics and Undersea Technology had executed a one-week real oceanic area experiment of underwater networking, communication, and acoustical tomography in Sizih Bay Marine Test Field. The experiment adopted 9 sets of underwater modem distributed within the range of 30 square kilometer to transmit, receive signals and collect CTD data. This research adopted part of the data gained from the experiment mentioned above to progress the feasibility test of acoustic tomography on current estimate to shallow water environment. By transmitting and receiving signals between stations, This research study the travel time difference between transmitting signals forward and backward caused by the flow field when using high frequency source in shallow water environment. This research estimated the average current speed and compared it to the weather buoy data from the Harbor and Marine Technology Center. This research discovered that most of the estimated results correspond to the weather buoy's ADCP data. Finally, this research adopted the method which does not require complex mathematics operation to estimate the two-dimensional flow field, and probe into what influence the angle between stations would bring to the deviation of estimating flow speed by using the Monte Carlo method.