In the current study, bioactivity-guided separation of the eight key antioxidant components of beer with Yuan’an yellow tea was accomplished by sequential alcohol precipitation, solvent extraction, macroporous resin absorption, and semi-preparative liquid chromatography. These antioxidant compounds were identified as (-)-epigallocatechin (EGC), caffeine, (-)-epigallocatechin gallate (EGCG), epicatechin (EC), 1,2,6-tri-O-galloyl-β-D-glucopyranose, (-)-epicatechin gallate (ECG), corilagin (Cor), and tryptophan (Trp) by ultra-high performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry (UPLC-Q-TOF-MS). Furthermore, EGC, EGCG, EC, ECG and Cor were the main antioxidant substances in beer with Yuan’an yellow tea, which collectively contributed up to 54.61% of its antioxidant activity. The contribution of EGCG was the highest, followed by EGC, ECG, EC and Cor. This study provides technical support for identifying the key antioxidant components in beer with tea and developing novel beer products with high antioxidant activity.