We propose an approach which combines component UML model and interface automata in order to assemble components and to verify their interoperability. We specify component based system architecture with component UML model, and component interfaces with interface automata. Interface automata is a common Input Output (I/O) automata-based formalism intended to specify the signature and the protocol level of component interfaces. We improve interface automata approach by component UML model, in order to consider system architecture, in component composition and interoperability verification methods. Therefore, we handle in interface automata, the connection between components, and the hierarchical connections between composite components and their subcomponents.