The component-based modeling technology was widely used in current combat simulation systems. The method of component-based modeling based on the FSM (Finite State Machine) was expounded in detail. With the method, the model of one armament was divided into multi sub-components which were modeled by FSM. And with the information communication among the components and the cooperated working, the combat process of the armament can be simulated. In the typical armament modeling, the design of the FSM models and the pseudocodes were given.