Abstract: In this paper, the requirements management based on use cases is theoretically explored, and a multi-layer use-case model is introduced, which combined with three levels of use cases and a single use-case refinement model. Through the practice in a software project, the multi-layer use-case model provides a good solution on how to control the requirements scope and change, and provides the balance of work assignment between customer departments, information management departments and software development outsourcing team.