Abstract: Under the guidance of “dual carbon” goals, the photovoltaic industry has undergone rapid development, and a large-scale wave of photovoltaic module retirement is imminent. The harmless disposal and resource recovery of retired photovoltaic cells have emerged as a prominent research focus in the field of new energy solid waste. Pyrolysis is a highly promising and efficient method for processing retired photovoltaic cells. Ethylene–vinyl acetate copolymer （EVA）, as the core encapsulation material of PV modules, directly affects the separation efficiency and product recovery value of retired modules during pyrolysis. Therefore, the pyrolysis mechanism of EVA needs to be clarified for the development of efficient pyrolysis recovery processes. Density functional theory （DFT） is adopted to construct an EVA model featuring a backbone with six carbon atoms, combining rate constant analysis to elucidate the pyrolysis mechanism of EVA. In the initial stage, EVA primarily undergoes the homolytic cleavage of the backbone C—C bonds and deacetylation reactions initiated by hydrogen transfer. The energy barrier of the five-membered ring transition state is as low as 166.06 kJ/mol, producing acetic acid and hydrocarbon radicals. After acetyl groups removing from the backbone, the long-chain hydrocarbon intermediates generated by pyrolysis undergo the C—C bond scission via homolytic cleavage and intramolecular hydrogen transfer. The lowest energy barrier is 284.26 kJ/mol, and short-chain hydrocarbons such as CH₄, ethylene, 1-butene, and free radicals are generated. Some intermediates further participate in Diels-Alder and substitution reactions to form aromatic compounds like benzoic acid, and the energy barrier of the rate-determining step is as low as 191.84 kJ/mol. Subsequently, acetic acid continues to decompose via hydrogen transfer reactions with an energy barrier of 274.61 kJ/mol, generating CO₂ and CH₄. The pyrolysis mechanism of EVA is elucidated at the molecular level, providing important theoretical support for the targeted pyrolysis regulation, high-value product recovery and process parameter optimization of EVA materials of retired photovoltaic cells.