OBJECTIVE：To establish the quality standards of Mongolian medicine Cynanchum thesioides. METHODS ：TLC was used for the qualitative identification of C. thesioides . According to 2015 edition of Chinese Pharmacopeia （part Ⅳ），the moisture，total ash and ethanol-soluble extract were determined. HPLC method was used to determine the content of thesioideoside in C. thesioides . RESULTS ：TLC spots were clear ，there were same yellow green fluorescent spots on the corresponding position of the sample （C. thesioides ）and control （thesioideoside）. In 22 batches of samples ，contents of moisture were 6.18％-12.97％，total ash were 4.64％-7.95％，ethanol-soluble extract were 12.46％-32.70％. The linear range of thesioideoside were 0.048-3.050 μg（R2＝ 0.999 9）. RSDs of precision ， stability， repeatability and durability tests were all less than 1％ . The recoveries were 104.03％-106.36％（RSD＝0.96％，n＝6）. The contents of thesioideoside in 22 batches of C. thesioides were 0.006 2％-0.130 5％. CONCLUSIONS：It is suggested that the moisture and total ash should not exceed 11.50％ and 7.50％，respectively；the contents of ethanol-soluble extract and the sioideoside are no less than 17.00％ and 0.05％，respectively. The established quality standards can be used for quality control of Mongolian medicine C. thesioides .