Abstract： Objective：To verify the important role of Radix Rehmanniae in the treatment of wasting-thirst disease by studying the frequency of Radix Rehmanniae in wasting- thirst disease related prescriptions and modern pharmacology. Methods：Relevant literatures and data retrieved from CNKI，VIP，Wanfang and PubMed databases were summed up and sorted out via Microsoft Excel 2010. In this paper， the application of Radix Rehmanniae in wasting- thirst disease related prescriptions， the application of different processed products of Radix Rehmanniae in treating wasting- thirst disease of different syndrome types and their difference were analyzed， and the active components of Radix Rehmanniae in the treatment of wasting- thirst disease and its hypoglycemic mechanism were summarized. Results： A total of 41 Xiaoke prescriptions containing Rehmannia glutinosa were obtained，of which 18 were unprocessed Radix Rehmanniae and 23 were processed Radix Rehmanniae glutinosa. And most of the prescriptions collected are from Tai Ping Sheng Hui Fang. Among the prescriptions treating different syndromes，Radix Rehmanniae was more frequently used in the prescriptions for deficiency of both yin and yang type and deficiency of both qi and yin type. Among different processed products of Radix Rehmanniae， unprocessed Radix Rehmanniae was more frequently used in the prescriptions for yin deficiency and dryness-heat type，yin deficiency and excessive heat type and deficiency of both qi and yin type；processed Radix Rehmanniae was more frequently used in the prescriptions for liver-kidney yin deficiency type，qi deficiency and blood stasis type and deficiency of both yin and yang type. According to the analysis of literatures of modern pharmacology， the main hypoglycemic components in Radix Rehmanniae were catalpol， rehmannia glutinosa polysaccharide and oligosaccharides. Conclusion： Both ancient classical prescriptions and modern pharmacological studies show that Radix Rehmanniae has a good therapeutic effect on wastingthirst disease.