《神农本草经》载知母性味苦寒为中品“，主消渴热中，除邪气，肢体浮肿，下水，补不足，益气”。以《神农本草经》中知母功效为纲，对其在《伤寒杂病论》经方中的配伍规律进行归类分析，发现知母“主消渴热中，除邪气”主要配伍石膏等，代表方剂白虎汤；“肢体浮肿，下水”主要配伍白芍、桂枝等，代表方剂桂枝芍药知母汤；“补不足”主要配伍酸枣仁等，代表方剂酸枣仁汤；“益气”主要配伍人参等，代表方剂白虎加人参汤。除《神农本草经》所载功效外，张仲景运用知母经方还有新的发展，如知母配伍麻黄、升麻、黄芩等组成麻黄升麻汤“除咽喉不利、唾脓血”。

The Shennong's Classic of Materia Medica records that Zhimu(Anemarrhenae Rhizoma),bitter in taste and cold in property in the medium-grade,“is mainly used to treat wasting-thirst and heat attack,to eliminate pathogenic factors,to relieve dropsy of limbs,to promote urination,to improve insufficiency and to replenish qi.” Based on the efficacy of Zhimu in Shennong's Classic of Materia Medica,this paper classified and analyzed the compatibility regularities in the classic formulas of Treatise on Cold Pathogenic and Miscellaneous Diseases. It was found that Zhimu is mainly combined with Shigao(Gypsum) to “treat wasting-thirst and heat attack,to eliminate pathogenic factors”,represented by Baihu Decoction（白虎汤）.Zhimu should be combined with Baishao(Paeoniae Radix Alba) and Guizhi(Cinnamomi Ramulus) “to relieve dropsy of limbs and to promote urination”,represented by Guizhi Shaoyao Zhimu Decoction（桂枝芍药知母汤 ）. It can be combined with Suanzaoren(Ziziphi Spinosae Semen) “to improve insufficiency”,represented by Suanzaoren Decoction（酸枣仁汤）. It is mainly combined with Renshen(Ginseng Radix et Rhizoma) “to replenish qi”,represented by Baihu Jia Renshen Decoction（白虎加人参汤）. In addition to the efficacy contained in Shennong's Classic of Materia Medica,ZHANG Zhongjing also has new development in the use of Zhimu. For example,Zhimu combined with Mahuang(Ephedrae Herba),Shengma(Cimicifugae Rhizama),Huangqin(Scutellariae Radix),etc. to constitute Mahuang Shengma Decoction（麻黄升麻汤）,which be used to treat “sore-throat,difficulty in swallowing,coughing of pus and blood”.