OBJECTIVE：To establi sh the quality standard of Yao medicine Pileostegia tomentella，and to provide reference for its quality control. METHODS ：Totally 10 batches of P. tomentella were collected from Guangxi area. The properties of P. tomentella were observed and microscopic identification was conducted for the transverse section of its stems ，roots and powder. TLC method was established by using 7-hydroxycoumarin as reference. The contents of water ，total ash ，acid-insoluble ash and alcohol-soluble extract in P. tomentella were determined. The contents of skimmin ，7-hydroxycoumarin and 7-hydroxy-8- methoxycoumarin in P. tomentella were determined by HPLC. RESULTS ：The root and stem surface of P. tomentella possessed obvious wrinkles ，hard texture ，slight smell and bitter taste ，and there were secretory cells and needle crystal cells in the cross section. The medicinal powder contained calcium oxalate needle crystal ，calcium oxalate square crystal ，sclerotic cell and starch granules. The results of TLC showed that the spots of the same color were found in the corresponding positions of chromatograms of test samples and 7-hydroxycoumarin control. In the 10 batch of P. tomentella ，the contents of water were 9.1％-11.8％；those of total ash were 3.6％-6.7％；those of acid-insoluble ash were 0.10％-0.44％；those of alcohol-soluble extract were 8.9％-14.0％.The linear range of skimmin ，7-hydroxycoumarin and 7-hydroxy-8-methoxycoumarin were 6.088-182.640，1.568-47.040 and 1.096- 32.880 μg/mL（all r not less than 0.999 7）. The average recoveries were 99.47％，101.07％ and 99.89％（RSD were all less than 2％）. RSDs of precision ，stability（24 h），reproducibility and durability tests were all lower than 2％ . The contents of 3 components such as skimmin were 1.337-9.534，0.348-2.236， 0.083-1.088 mg/g，respectively. CONCLUSIONS ：It is preli- 201705） minarily proposed that the content of water in P. tomentella is not more than 12.0％ ；that of total ash is not more than 7.0％；that of alcohol-soluble extract is not less than 8.0％； E-mail：luguoshou@foxmail.com that of ski mmin is not less than 1.30 mg/g；that of 7-hydroxy- coumarin is not less than 0.30 mg/g；that of 7-hydroxy-8-methoxycoumarin is not less than 0.06 mg/g.