Abstract: To determine the contents of p-coumaric acid and ferulic acid in Rhizama Phragmitis by HPLC for quality evaluation. Rhizama Phragmitis alkaline alcoholic solution exact of p-coumaric acid and ferulic acid was refluxed. An HPLC method was developed by using a Diamonsil C₁₈(4. 6 mm×250 mm, 5 μm)column, and the mobile phase of acetonitrile and 0. 3% acetic acid with linear gradient elution at a flow of 1. 0 mL/min and UV detection at 310 nm. Calibration curvers of p-coumaric acid and ferulic acid were linear over the range of 0. 2-200 μg/mL and 0. 1-120 μg/mL respectively. . Average recoveries were(96. 9±2. 91)% and(98. 7±1. 78)%, respectively. The average contents of p-coumaric acid and ferulic acid expressed as mean±sd(max-min)were(0. 88±0. 16)%(1. 21%-0. 70%)and(0. 41±0. 035)%(0. 49%-0. 36%)in 15 batches of Rhizama Phragmitis. The established method will be beneficial to the quality evaluation of Rhizama Phragmitis.