• An in-capillary ABTS+-sweeping MEKC-DAD method was developed. • The sensitivity was enhanced 17–167 folds. • Trace antioxidants in natural products can be screened by this method. • This method was sensitive and automated. An in-capillary 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)-sweeping micellar electrokinetic chromatography-diode array detector (ABTS+-sweeping MEKC-DAD) method was developed and successfully applied to screening and quantifying antioxidative ingredients from natural products. The parameters affecting sweeping and separation were optimized including components of background electrolyte and sample matrix. Comparing with previously reported MEKC, the sensitivity enhancement factors of trace natural antioxidants obtained by this proposed method were from 17 to 167. The limit of detection was as low as 6 ng·mL−1. The results of other validation parameters including linearity, reproducibility, accuracy and recovery were satisfactory. Seven compounds including schizandrin, schisandrol B, schisantherin B, schisantherin A, schisanhenol, deoxyschizandrin, schisandrin B were identified as the main antioxidants in Schisandra chinensis. It was demonstrated that this developed in-capillary ABTS+-sweeping MEKC-DAD is simple, sensitive, reliable and rapid method for screening and quantifying trace antioxidants from natural products. [ABSTRACT FROM AUTHOR]