This paper proposes an approach to reusing COTS software products to construct software components. This approach supports software component designers to develop software components rapidly by reusing COTS software products under a uniform software component model. In this paper, we call those software components by reusing COTS software as COTS-Based software components, in short COTSB components. A software component specification will be defined to serve COTSB components. It can be applied on cross platforms. Moreover, a software re-engineering technique named wrapping will be used to support reusing COTS software as COTSB components. In this paper we also adopt two existed design patterns - Adapter and Abstract Factory [2] as a systematic design approach for designing and implementing COTSB components. It can be regarded as a design blueprint for the COTSB component designers.