In this paper, air-defense simulation model, called "DADSim", will be introduced. DADSim(Distributed Air Defense Simulation Model) was developed by Modeling&Simulation Lab of K.N.D.U.(Korea National Defence Univ) Weapon Systems Department. This model is an analysis-purpose model in the engagement-level. DADSim can simulate not only the global air-defense or Korean Peninsula but also the local air-defense or a battle field. DADSim uses the DTED(digital terrain elevation data) LeveII it for the representation of peninsula terrain characteristics. The weapon systems cooperated in the model are low/medium-range missile systems such as HAWK, NIKE, SAM. DADSim was designed in the way of object-oriented development method, implemented by C++ language. The simulation view is an event-sequenced object-orientation. For the convenience of input, output analysis, GUI(Graphic User Interface) of menu, window, dialog box, etc. are provided to the user, For the execution of DADSim, Silicon Graphic IRIX 6.3 or high version is required. DADSim can be used for the effectiveness analysis of­defence systems. Some illustrative examples will be shown in this paper.