This study suggested a knowledge theory, theoretical framework and general principles in methodologies for library and information science by theoretically weighing domain analysis. The central concept to domain analysis are a subject knowledge constituting the domain and a discourse communities to share their knowledge. Therefore the study described a definition of domain and explained domain in ontological, epistemological, and sociological dimensions, proposed eleven approaches available in domain analysis. And the study argued the implications of domain analysis for library and information in position of socio-cognitive view and pragmatic realism.