A capillary zone electrophoresis(CZE) method was established for the separation and determination of three effective compounds such as caffeine,theobromine and theophylline in alkaloidal samples.The sample was separated on an uncoated silica capillary(75 μm i.d.×60 cm，effective length:50 cm) using pH 9.0 20 mmol?L-1 borate containing 4 mmol?L-1 beta-cyclodextrin (β-CD) as running buffer.The pressure of injection was set at 0.5 psi and the time was set 5 s.The detection wavelength was 273 nm.A voltage of 16 kV was applied at 25 ℃.Under the optimal conditions,good linear relationships were observed between peak areas and alkaloidal concentrations in the range of 0.036-0.288 g?L-1, with correlation coefficients not less than 0.998 4.The RSDs of the peak area were not more than 3.2%.The limits of detection (LODs) were not more than 2.7 mg?L-1.The average recoveries were in the range of 97%-104%.This method is simple,quick and less reagent-consuming,and is suitable for the separation and determination of the three alkaloids in real samples.