桂枝麻黄各半汤与桂枝二麻黄一汤是汉代张仲景所制桂麻合方。二方药物组成完全相同，均用于治疗表郁轻证，但药物剂量与服法却存在差异。通过分析二方证候、药物剂量和煎服法的异同，揭示桂麻合方的方证关系。发现在病机相同的背景下，症状轻重不同，张仲景用药剂量和服法也随之变化，体现方证合拍、用药准确、精细入微的辨证论治精神，对临床遣方用药具有重要指导意义。

Guizhi two Mahuang one Tang and Guizhi Mahuang geban Tang were made by Zhang Zhongjing.The composition of the two formulas is the same，which is used to treat light epidermis depression syndrome.But doses and decocting and dosing method are different for these two formulas.By analyzing the difference and similarity of syndromes，medicine dose and decocting and dosing method，corresponding relations between Guizhi Tang and Mahuang Tang formulas are revealed.It was found that under the background of the same pathogenesis，the dosage and decocting and dosing method were different in Zhang Zhongjing's prescription，reflecting the unity of prescription and syndrome，the accurate application of medication and dialectical discussion of the treatment of disease.This has very important guiding significance for composing formulas and choosing medicine in clinical practice.