A fully automatic quantitative capillary electrophoresis system,which consists of a lab-made auto-sampler equipped with a 10 nL rotary type injector and a lab-made thermostat with cooling capacity,was developed.The accuracy and precision of the method were greatly improved compared with that of the conventional capillary electrophoresis（CE）.This article explored the feasibility of determination of benzoic acid,methyl p-hydroxybenzoate（MP）,ethyl p-hydroxybenzoate（EP）,propyl p-hydroxybenzoate（PP） and butyl p-hydroxybenzoate（BP） in cosmetics by fully automated quantitative micellar electrokinetic capillary chromatography（qMEKC）.The contents of MP,benzoic acid,EP,PP and BP in body cream and exfoliating gel were determined with a mobile phase of 15 mmol/L borax buffer and 100 mmol/L SDS（pH 9.3） mixture and a separation voltage of 20 kV.Good separation for the five preservatives was achieved under the optimal conditions,with RSDs of peak area lower than 2%.This method is rapid and accurate,and may be employed in the quality control of preservatives in cosmetics.