According to TCM theory，the kidney stores the essence，and the essence produces the marrow，which fills brain，nourishes bone，and generates blood. The kidney，the essence and the marrow together constitute ‘the kidney-marrow system，among which the kidney is root，the essence is key，and the marrow is pivot. Prosperity or decline of the kidney essence determines profit or loss of the marrow，and its the physiological and pathological basis of brain being sea of marrow，kidney governing bone，and essence transforming into blood. Simultaneously，stem cells and the kidney essence are proved to correlate closely in modern TCM study，embodying the substance and function characteristics of “the kidney-marrow system”.