The quantitative analytical method for the content of dioscin in Dioscorea rhizoma using a high performance liquid chromatography(HPLC) system was established for its quality control. After extracting Discorea rhizoma flour with ethanol, dioscin was separated though an ODS column with a flow rate of 1.0ml/min of acetonnitril-methanol-0.01 M phosphate buffer (pH 5.0)(6:3:1, v/v%), and the amount of dioscin was detected at 210nm. Relation time of dioscin in HPLC chromatogram were about $7.45{pm}0.34;min$ and calibration curve showed good linearity at concentrations from 0.1 to 2.0 mg/ml of dioscin. When 5 commercial Dioscorea rhizoma flours were analyzed by HPLC, the peak for dioscin was well separated from others in ethanol extract of Dioscorea rhizoma, and the amount of dioscin was in the range from 0.076 to 0.142(w/w)%.