DEVS provides a modular and hierarchical system modeling and simulation framework but lacks the ability of behavior modeling. Statecharts extend finite state machine and do outstanding jobs in modeling complicated behavior of systems by means of visual and flexible state-transition diagrams. Hence, a composable modeling approach, embedding the statecharts into DEVS to complement each other, is raised. It can be used to build complicated discrete control system. DEVS, as a system modeling framework, provides simulation logical support and statecharts expand the event interaction mechanism of DEVS which can be used to modeling system behavior logic. The paper details the syntax and semantics of statecharts and DEVS, and emphasizes on the mechanism of embedding statecharts into DEVS. The advantages of building discrete control system models by embedding statecharts into DEVS are illustrated by an application example.