With the wide application of Internet in elearning, the requirement of reusable, sharable learning objects and adaptive learning strategies becomes common ground. Traditional methods of Web resources publishing and managing such as free publishing or building application systems for special purposes are not good at fast discovering and aggregating knowledge. This paper discusses Meta-data structure in elearning, which facilitates searching, managing and linking granules of learning contents. Applying Web services and UDDI techniques, a system of knowledge management on Web based on Meta-data is proposed and some questions in application are discussed.