In the present study, a simple and efficient approach based on the online extraction-high performance liquid chromatography coupled with ABTS antioxidant assay (OLE-HPLC-ABTS) was established to quickly and directly analyze the antioxidants in S. baumii. Through this system, the HPLC mobile phase via a guard column packed with a S. baumii sample was used for online extraction (OLE). The separation was performed on an Agilent Poroshell EC-C18 column with a gradient elution using 0.1% formic acid (A) and 0.1% formic acid-acetonitrile (B) as mobile phase systems and detected at a wavelength of 254 nm. Then, the separated compounds were reacted with the antioxidant solution (ABTS), and the response was recorded at a wavelength of 400 nm. The developed analytical method was successfully applied to S. baumii samples, and eight antioxidants were identified. The established system integrated the online extraction, separation and online antioxidant detection, which is rapid, efficient, and suitable for the rapid screening of antioxidant compounds from solid sample mixtures.This journal is © The Royal Society of Chemistry.