In order to gain a better understanding of the relationship between liver and spleen, this article analyzed classic literature regarding it and tired to find out the external and internal cause of its evolution. It can be concluded that theoretical changes of their relationship originated from the alteration of Traditional Chinese Medicine(TCM) theories. The internal cause are different TCM theories in different ages and clinical experience and the external causes comes from social demand and major trend of thought of the society. In summary, in Tang and Han dynasties, the relationship between earth and wood was emphasized; in Song, Jin and Yuan dynasties, the relationship between heat and original qi was put into much emphasis; in Ming and Qing dynasty, practitioners emphasize the relationship between spleen and liver, while after that, there being a theory of the governing function of liver on spleen and liver. The relationship between liver and spleen are thus closer step by step. This paper is beneficial for people to better understand liver and spleen, which could also contribute to TCM development and viscera theory construction.