"The Suan-Jiao-Ku-Gan method"originated from the synopsis of the Golden Chamber written by ZHANG Zhongjing,which is an effective method to treat liver deficiency.Based on the theory of five elements and the Kuyu Buxie principle,this paper explores the relationship between the five elements.It deeply studies the in-ternal therapeutic mechanism of"the Suan-Jiao-Ku-Gan method"for liver deficiency.The treatment involves the strategic application of sour flavors to nourish the liver,the searing of bitter flavors to expel pathogenic factors,and the balancing act of sweet flavors to moderate the treatment.The practitioners can flexibly adopt the method to reinforce the mother-organ in case of deficiency and to purge the child-organ in case of excess.In this paper,Suanzaoren Decoction is taken as the representative agent to further analyze"the Suan-Jiao-Ku-Gan method",of-fering insights to enhance its utility in clinical practice.