Stakeholder cooperation is important for conducting a successful software project. The software industry has increasingly expanded its adoption of COTS components for complex applications. The stakeholders of COTS-based projects differ considerably from these of conventional custom development projects. All members of the project team should print the COTS-inclusion concept deeply within their mind. There are also great changes in roles and needed skills. For COTS-based project, it is crucial to understand all classes of stakeholders, their responsibilities, and inter-collaboration relationships by contrasting with traditional software development. According to the characteristics of COTS-based project, focusing on the differences, this paper is regulated to elaborate on all stakeholder roles and corresponding responsibilities, the differences with custom-development project, and the cooperation relationship between stakeholders.