Abstract: A high performance liquid chromatographic method for the separation and determination of curcumin, demethoxycurcumin and bisdemethoxycurcumin in Curcuma longa L, and its preparation is reported in thispaper. Determination was carried outunder the following conditions: column: YWG-C₁₈H₃₅, 10 μm 200×4.6 mm; N (naphtha-lene) =40000/m; eluant: THF—H₂O—glacial HOAc (36:58:6, V/V/V); pressure: 110 kg/cm²; flow rate: 1 ml/min; paper rate: 5mm/min; UV-254 nm; naphthalene was used as an internal standard. This method is quick and simple, and other yellow soluble substance of Curcuma longa L. did not interfere. Four crude drug samples obtained from Guangdong, Jiangxi and Sichuan, total curcuminoid extract and curcuminoid capsula were determined with satisfactory results.