The evasive capability of a conventional submarine against a Light Antisubmarine Warfare (ASW) torpedo was studied. Unified Modeling Language (UML) was used for analysis and design of the simulation system. Then, the models of antisubmarine torpedo, submarine, self-propelled acoustical decoy and noise jammer were established by using Discrete Event System Specification (DEVS) formalism. Analysis was made to the effect of the submarine's propulsion system and torpedo countermeasure system on its evasive performance. The results are valuable for the Simulation Based Acquisition (SBA) of a submarine system.