This article traces the origin of“kidney is the gate of the stomach” in Huang-di’s Inner Classic, analyzes the interpretation of this provision by doctors in various periods. It holds that the theoretical connotation of “kidney is the gate of the stomach” should include“spleen and stomach is the source of qi and blood, the hub of qi ascending and descending” and“the kidney is the key to the ascending and descending turbid of spleen and stomach and the balance of Yin and Yang.” The treatment of functional constipation should be based on the two core organs of“spleen and stomach” and “kidney”. It also takes “The treatment of the spleen and stomach should be based on the qi ascending and descending, qi and blood” and “the treatment of kidney should be based on Yin and Yang” as the core therapeutic principle, further play the guiding role of the theory of“kidney is the gate of the stomach”, in order to help the clinical syndrome differentiation of functional constipation.