Abstract: The concept of Xin appears very often in Mencius. In order to analysis the meaning of the concept of Xin, we should itemize the concept. The concept of Xin in Mencius indicates psychology activity. The interpretation of the concept of Xin turned to the tendency of metaphysics after Han dynasty, which was based on the scholar’s philosophy view. If we want to get the reasonable interpretation, we should analysis the relation between mind and material.

Key words: Mencius, Concept of Xin, the relation between mind and material