With the development of the information age, the demands for computer software have become increasingly complex. Increasing scale, with the development of enterprises, and the reorganization of the work process, which make the requirements change become increasingly frequent. Formal theoretical foundation based on rCOS, leads to integration and refinement for Volere requirements process model. According to the RUP process, a trusted Simple Volere Requirement Model has been constructed to solve the requirements change as a very effective way.