In this paper, the generation mechanism of oxidation products during the oxidation of the SEBS/PP blend in air atmosphere was investigated using temperature-dependent FTIR combined with 2D correlation infrared spectroscopy. DSC, TG, and PCMW2D found three processes associated with SEBS/PP oxidative degradation. The 2D correlation analysis was used to study the sequential order of groups’ movement of reactants and oxidation products involved in the main oxidation. It was found that the main oxidation started from the molecular chains of PP and EB blocks of SEBS. It firstly forms C?O?C structure between the molecular chains of PP and the EB blocks, resulting in the cross-linked structure. Aliphatic ketones were formed via the β-scission of the main chains of PP or the EB blocks. Then, aliphatic ketones were converted into aliphatic esters. After the above reactions, the S blocks of SEBS began to oxidize. The S blocks are generated into aromatic ketones through β-scission. The formation of lactones in the molecular chains of PP and EB blocks was followed via the radical biting back. Finally, aromatic ketones generated from the S blocks were converted into aromatic esters through the reactions of Norrish I, the radical coupling, and so on.