Knowledge sharing is the core of knowledge management (KM). Recently, a lot of literatures and materials showed that knowledge sharing has become a very important part of KM research. In this paper, research literatures on knowledge sharing have been collected from 1996 to 2005. After analyzing and classifying all these literatures, we think that they centered knowledge sharing from four angles: the economy of knowledge sharing, object of knowledge sharing, main body of knowledge sharing and means of knowledge sharing. Meanwhile, review on these four aspects has been conducted. Finally, the future research on knowledge sharing is proposed.