Because the evaporation of seawater and the onflow of the sea breeze, the atmospheric humidity dimension with altitude in range of offing, it makes Atmospheric Guide. The high speed data link of unmanned aerial vehicle（UAV）is affected badly by the multiple channels of atmospheric guide in sea navigating. The APM model is made for computing the transmittal loss, which shows that the energy fastens on the Atmospheric Guide, so strong branches and dispersion are caused. By combining the reality radar echo figures and the mechanism, the model of dispersion discrete multiple channels is given. The course of academic analysis and idiographic actualizing methods of the model are expatiated, which can provide an important theory basis for the measurement of the channel characteristic.