Getting a proper set of reusable requirements is an important milestone for successful software product line (SPL) practice. But modeling SPL requirements is usually more complex and difficult than modeling requirements for individual applications because it often involves systematically exploring commonality and variation across a set of applications. This paper presents a feature-oriented approach to modeling and reusing SPL requirements. A framework of the feature model is first proposed from five aspects, namely, basic structure, variation representation mechanism, variation binding time, variation constraint mechanism and quality feature analysis. Then, a customization-based reusing method is suggested, and a feature-oriented domain modeling method (FODM) is presented, including a concrete form of the feature model and a modeling process for it. At the end, a case study of a real domain is used to validate the feature model framework and demonstrate FODM.