Abstract：From the perspective of origin and development of academic sphere，the author analyzed and fully explained differences between“spleen yin deficiency”and“stomach yin deficiency”through discriminating differences and similarities of disease， treatment methods， and prescriptions. The author thought that“spleen yin deficiency”and“stomach yin deficiency”share the same origin of theory， both of which are supplement and development of LI Dongyuan's Piwei Lun. Meanwhile，for later generations，the spleen is often referred to as the stomach，and vice versa；treatment methods of the spleen are mixed with those of the stomach； that is because the spleen and stomach both pertain to middle energizer. However，the spleen and stomach differ in physiological function，and“spleen yin deficiency”and“stomach yin deficiency” differ in main manifestations . The author further noted that in the treatment of the spleen and stomach diseases based on syndrome differentiation， WANG Bangcai inherits methods from ZHANG Zhongjing and YE Tianshi， and well digests MIU Xiyong's theory of spleen yin. What's more， the author presented several medical cases in order to demonstrate WANG Bangcai’s application.