Techniques for modeling and simulating the underlying channel-PHY play an essential role in understanding network protocol and application behavior of tactical data link (TDL). Inappropriate modeling and simulation of channel-PHY make the results incredibility. In this paper a model architecture of channel and physical layer is described in NS-2 (Network Simulator version 2). The five key technique of lower layer modeling are studied and analyzed, including FSM (Finite State Machine) model, delay computing, wireless propagation forecasting, power computing for interference signal and error checking for receiving signals. By using simulations and measurements from two different TDL test beds, we show that the channel-PHY modeling and simulation is on the importance of TDL simulation.