Education and training are expected to change dramatically due to the combined impact of the Internet, database, and multimedia technologies. However, the distance learning is often impeded by the lack of effective methods to retrieve specific parts of a lecture by contents. This paper introduces a new approach to realize the content-based lecture retrieval on the Web. The approach involves: (1) The XML(eXtensible Markup Language)-based semistructured model not only to represent lecture contents but also to exchange them on the Web; (2) The technique to build structural summaries, i.e., schemas, of XML lecture databases. The structural summaries are useful for browsing and querying the database, building indexes, and enabling query optimization; (3) Index structures to speed up the search to find appropriate lecture contents.