Framework is an important approach to large-grained software reuse. Object-Oriented frameworks are widely used through instantiation, but some shortcomings of object-oriented framework were mentioned during related researches and practices. Component-Based software framework (CBSF), which belongs to black-box framework, is adopted to solve these problems. In CBSF, component is chosen to substitute for collaborated class to increase the granularity of framework's element, and hot spot is implemented by component interface calling and components composition. Role extension form of CBSF is discussed, in which role is a special component that need to be instantiated, and can be categorized into abstract component and template. During the CBSF develop process, architecture patterns, design patterns and parameterizations approaches are helpful to design role extension for different domain variability types. Some issues on composing application components based on the role extension form are also discussed in this paper.