Abstract: To explore the origins and theoretical significance of stomach yin theory. It is belived that the stomach yin theory originated from The Yellow Emperor's Inner Classic and Zhongjing， inherited from Hejian school， led the Ming Dynasty doctors， and finally promoted by Ye Tianshi and other physicians of Qing dynasty. As a unity of opposite concept of the spleen yang theory， it has an independent theory system， dialectical guidelines and treatment methods， improving and supplementing the spleen and stomach theory in TCM.