A large volume sample injection(LVSS)-reverse current flow accumulation capillary zone electrophoresis(CZE) method was used for the simultaneous separation and determination of magnolol,chlorogenic acid and caffeic acid in Qinggan Lidan oral.The result indicated that a best separation of three materials were obtained on an uncoated fused silica capillary column(50 cm×50 μm，effective length 36 cm) by using background electrolyte containing 40 mmol/L Na2B4O7，20mmol/L NaH2PO4，pH 9.0).The detection wavelength was set at 220 nm，with the separation voltage at 16 kV，the sample injection voltage at-12 kV and the injection time in 356 s.Under the optimum conditions， the separation of three compounds was performed within 20 min with relative standard deviations(RSDs) of peak area less than 4%.The detection limits(S/N=3) of magnolol，chlorogenic acid and caffeic acid were 184.2，36.07，77.99 ng/L，respectively.