The feature model has been widely adopted as a domain requirements capturing model by most of the current domain engineering methods. But these methods lack a well formatted framework for the feature models which they use. This has led to the redundancy and confusion in feature model representation between different domain engineering methods, and has made domain analysts difficult to built feature models effectively in practice. In this paper, a uniform framework of feature model is presented from the aspects of basic structure, variability representation and constraint mechanism, and variability binding time. A concrete form of this abstract framework is also given based on the different type of features existing in requirements (service, use case, function, and behavior characteristic), and the relationship among them. Then, combining with a real software domain, the modeling process of the feature model is discussed systematically. This approach will be beneficial to successful domain modeling practices.