With the development of the network technology, the scale of the information system is becoming larger. Component software engineering is the hot point method supporting the development of such kind of application based on network computing model. Java Beans is a standard for software components. For develop high quality components, this paper proposes a toolkit -- MChecker for checking the consistency between the Java Beans semantic constraints and its implementation. MChecker uses a logic-based language -- Java Beans Description Language for describing the bean's semantic constraints. Consistency checking is based on a dynamic model checking approach. A generator is used to generate the checker automatically for a source bean. A wrapper is used to make the source support the check process. We in the paper illustrate the system architecture, the key technology and the core algorithm. Some experimental re sults are showed by examples.