Oxidative stability is of particular importance to maintain the morphology and adjust physicochemical properties of pitch-based carbon products. Due to the complex composition of pitch, the oxidative reactivity of the pitch components has rarely been reported to date, so that the oxidative stabilization conditions of pitch have been mainly selected from experience. In the study, a coal tar pitch was fractionated into toluene-soluble (TS), toluene-insoluble and pyridine-soluble (PS), pyridine-insoluble and quinoline-soluble (QS), and quinoline-insoluble (QI) fractions. The molecular structural features of each fraction and their reactivity with oxygen at varying oxidation temperature were characterized and evaluated. The results reveal that light fractions (TS and PS) with more alkyl side chains exhibit a higher reactivity at the low oxidation temperature range from 200 to 250 degrees C, leading to the formation of more cross-linked structures. Meanwhile heavy fractions (QS and QI), with relatively rich isolated aromatic hydrogen, seem to be remarkable in O-2 uptake and the formation of C-O structures until the oxidation temperature rises above 250 degrees C. Insight into group composition of the pitch allows predicting its oxidative stability characteristics and further allowing it to quickly fine-tune operational conditions for time-effective and energy-saving stabilization.