The 50% aqueous ethanol extracts of petals of Rosa gallica collected in Xinjiang province, China, exhibited potent inhibitory effects against alpha-amylase and alpha-glucosidase. As the active principles, seven hydrolysable tannins were isolated from this species for the first time and elucidated by NMR and ESI-TOF-MS analysis. Quantitative analysis by ultra-performance liquid chromatography demonstrated that the contents of these hydrolysable tannins were 3-5% of the dry weight of the petals, and the hydrolysable tannins must be related to the medicinal utilization of this species.