Abstract: 1-(α-Naphthylmethy)-2-methyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolinehydrochloride (code No, 86040)is a new kind of calcium antagonist. It has(+)and(一)enantiomers.Accordingly .the resolution and quantification of these two enantiomers have received agreat deal of attention,In this report the application of direct HPLC separation and semipreparation tothe determination of the enantiomeric composition of the new drug are described. All analysis andsemipreparation were performed with 25 cm×4. 6 mm i.d, 25 cm×8 mm i,d.and 30 cm×8 mmi.d. stainless steel column packed with a chiral β-cycledextrin bonded phase. Detection wavelengthwas 284 nm, The optimal composition of the mobile phase was EtOH─pH 4.0 phosphate buffer(35:65) at flow rate of 0. 3 ml·min^-1 for analysis and l.0 ml·min^-1 for semipreparation. Theseparation factor of the enantiomers was l.25. Purity of the semipreparation was 8l.4%,Quantityof semipreparation was 1 mg. This procedure was simple ,rapid and gave good resolution,The effectsof the composition of mobile phase, pH value, flow rate and column temperature on the resolution hadbeen sudied.