Abstract: Self-microemulsifying drug delivery system (SMEDDS) can significantly improve the oral bioavailability of water-insoluble drugs with diversified forms of administration, which has shown great application prospects in promoting the development of oral drug delivery system with high bioavailability. There are still some problems in SMEDDS such as inconvenience of storage and transportation, poor stability, and limitations of drug release evaluation. Recently, with the development of new materials and new technology in drug preparation, there have been an increasing number of researches on new pharmaceutical preparations such as solid self-microemulsifying delivery system and supersaturated self-microemulsifying delivery system, which can make up the deficiency of traditional SMEDDS and make use of its advantages. This paper reviews the excipients composition, oral absorption mechanism, solidification methods and release evaluation methods of SMEDDS.