[Objective] To study the basis of treating constipation with Shaoyao Gancao Decoction.[Method] Ancient and modern herbal and experience of famous doctors literature of Shaoyao Gancao decoction,Shaoyao(Peony) and Gancao(licorice) are reviewed and summed up.[Results] Shaoyao(Peony) and Gancao(licorice) themself have a certain purgative effect.Shaoyao is good at regulating abdominal qi and blood,"removing blood stasis and lump accumulation",eliminating abdominal evil,and thus plays a laxative effect.Gancao is good at detoxification,eliminating the toxin of stool,and thus plays a antitoxic and laxative effect.For constipation Shaoyao Gancao decoction is composed of raw Shaoyao and raw Gancao at a ratio of 3:1 to 2:1,and the general amount of raw Shaoyao is about 30g.[Conclusion]Shaoyao Gancao decoction has a good laxative effect,alone or its modified is suitable for a variety of constipation syndrome types.