With the CM-β-CD as a chiral selector to separation of chiral drugs by capillary electrophoresis, but which exist the problem of low separation selectivity, the asymmetry of the peaks, the adsorption of the sample molecules, and the instability baseline. A cyclodextrin derivatives similar with ionic liqid was prepared by the cation exchange reaction of CM-β-CD with 1-butyl-3-methy-limidazolium bromine ionic liquid. And study the application in capillary electrophoresis, that is as a chiral selector to separation of chiral drugs. Compared with CM-β-CD, the results showed that the separation selectivity remarkably increase, improve the peak shape and the baseline basically stable, obtained the ideal separation effect.