Worldwide museums are facing the challenge of applying knowledge management to digital archives projects to unify content acquisition, creation, organization, reusing, and publication among individuals, departments, and projects for long-term business prospective. We propose a unified knowledge-based content management approach that consists of a unified knowledge content process, a knowledge-based content management system and multi-layer reusable knowledge content structures. EER model was applied to effect integrate the global knowledge-based content management system and express multi-layer reusable knowledge content structures in digital archives of museums. A practical system was implemented to provide a unify knowledge management environment that the knowledge content creation, management, sharing, reuse, and accessing among all projects, specialists, content, technologies, and applications can be realized.