Abstract: Separation of enantiomers of 4 quinolones (ofloxacin,lomefloxacin,sparfloxacin,and gatifloxacin) were preformed simultaneously by capillary electrophoresis with copper(Ⅱ)-L-isoleucine as chiral resolving agent.Various factors influential to the efficiency of separation,including kinds of chiral resolving agent,ratio and concentration of chiral resolving agent,kinds of buffer solutions,pH and concentration of buffer solution,kinds and amount of organic additives,were studied and optimized.The enantiomers of ofloxacin and gatifloxacin were completely separated in 30 mmol·L-1 Na2B4O7-HCl buffer solution of pH 8.5 containing 8 mmol·L-1 L-isoleucine solution and 4 mmol·L-1 CuSO4 solution,the enantiomers of omefloxacin,sparfloxacin,and gatifloxacin were completely separated in 20 mmol·L-1 Tris-Na2B4O7 buffer solution of pH 9.0 containing 20 mmol·L-1 L-isoleucine solution,10 mmol·L-1 CuSO4 solution with addition of 5% by volume of acetonitrile.