The processing of Longdan（Gentianae Radix et Rhizoma）has a long history. There have been processing methods such as net processing，cutting，stir-frying，ginger processing，wine processing and liquorice processing. The processing specifications and methods have been simplified with historical changes，and now ginger processing and licorice processing are no longer used. The chemical constituents of Longdan（Gentianae Radix et Rhizoma）mainly include iridoids，flavonoids，triterpenoids，alkaloids，volatile oils，polysaccharides and some trace elements. It has many biological activities such as anti-inflammatory and analgesic，anti-tumor，neuroprotection，liver protection，anti-oxidation，hypoglycemic and lipid-lowering effects. After the processing of Longdan（Gentianae Radix et Rhizoma），the structure of iridoid glycosides will undergo decarboxylation，oxidation，cyclization，evaporation and oxidation of volatile oil components，and the contents of some trace elements will change，thus changing its medicinal properties and enhancing its efficacy. After stir-frying，Longdan（Gentianae Radix et Rhizoma）can weaken the coldness，and wine-processed Longdan（Gentianae Radix et Rhizoma）can enhance the pharmacological activities such as liver protection. In this paper，the processing changes of ancient and modern Longdan（Gentianae Radix et Rhizoma）and the effects of different processed products on chemical constituents and pharmacological effects were studied in order to provide the help for the standardization of traditional Chinese medicine Longdan（Gentianae Radix et Rhizoma）.