This paper expounds the understanding of “Bu Ke Yu Yao” in the clauses of ,Treatise on Exogenous Febrile Diseases,. The two annotations of the clause in the unified textbook are “do not use other drugs” and “non-residual dregs of a decoction”. By using the method of hermeneutic cycle within clauses， between clauses and between texts， the meaning of “Bu Ke Yu Yao” is studied and evaluated in this paper. Through the analysis of the syndrome of Didang Pill， entering the hermeneutic cycle of TCM classical text understanding and clinical practice interpretation and achieving the hermeneutic goal of practice， it is found that its meaning should be “do not overuse drugs”.