Objective To develop a HPLC method for determining the content of riparsaponin in Homonoia riparia Lour.Methods The determination was performed on the HYPERSILBDS-C18(200 mm?4.6 mm,5 ?m) with mobile phase consisted of acetonitrile-water(75∶25) at a flow rate of 1.0 ml/min.The detection wavelength was set at 203 nm,the column temperature was 30 ℃,and the column pressure was 10.0 MPa.Results There was a good linear relationship for riparsaponin over the ranges of 5 to 500 ?g/ml(r=0.999 8).The average recovery was 99.44%,and RSD was 0.52%(n=15).Conclusion The method has good reproducibility and high precision.It can be applied in quality control of Homonoia riparia Lour.