Based on the analyzing of the internal relationships among Constructivist Learning Theory, Humanism Learning Theory, Group Dynamic Theory and Learning Community theory, as well as their instructive significances for establishing an e-learning platform, this thesis discusses the construction of an e-learning platform at different levels from the perspective of knowledge management, and proposes the building of a theory model as well as a technology model of the e-learning platform based on some social software including blog, with the help of some new services and new concept of web 2.0.