This research explores the structural composition and antioxidant abilities of pectins extracted from Adenophora tetraphylla (Thunb.) Fisch. Pectins, which are a complex group of acidic polysaccharides, exhibit various biological activities due to their unique structural domains. Following aqueous extraction, the pectins underwent sequential purification using ion exchange and gel permeation chromatography techniques. FT-IR and NMR techniques were used to elucidate their structural characteristics. The structural investigation was enhanced through the application of multiple characterization methods: Congo red binding analysis, circular dichroism measurements, and scanning electron microscopy imaging. Among the isolated pectins, WATP-A2b (22.5 kDa) and WATP-A3b (49.8 kDa) demonstrated significant variations in their structural domain organization, comprising different ratios of homogalacturonan, rhamnogalacturonan I, and rhamnogalacturonan II. WATP-A3b displayed the most potent antioxidant performance among the tested pectins, effectively scavenging all three free radical species, which may be correlated with its higher galacturonic acid proportion and substantial rhamnogalacturonan I domain presence. These experimental results provide valuable insights into the correlation between structural characteristics and biological functions of pectins derived from Adenophora tetraphylla and their potential applications in healthcare.