This study investigated the characteristics of O₃ and its precursors in Dongguan during the autumns of 2018 and 2022. By integrating observational data, backward trajectory analysis, and box model simulations, we examined the changes in O₃ and precursor concentrations, O₃ formation pathways, and the evolution of control regimes during both polluted and clean periods, which provided insights into ozone pollution mitigation. The average O₃ concentration in Dongguan was higher in autumn 2022 than in 2018, whereas both the average concentrations of nitrogen oxides (NO_x) and volatile organic compounds (VOCs) decreased in 2022. Alkanes accounted for the largest proportion of total VOCs (TVOCs) in both autumn periods, while aromatics and alkenes contributed the most to ozone formation potential (OFP). Notably, the contribution of biogenic VOCs (specifically isoprene) to OFP increased from 6.0% in 2018 to 12.1% in 2022. Comparative studies between polluted and clean periods revealed that TVOC concentrations during polluted periods in 2018 (73.7×10^-9) and their growth rates (148.5%) were significantly higher than those in 2022 (26.1×10^-9 and 67.0%), driven primarily by alkanes and aromatics. In 2018, the OFP growth rate of alkanes was highest during the polluted periods, whereas aromatics dominated in 2022. Box model simulations revealed that the enhancement of O₃ formation rates (16.6×10^-9/h) was notably higher in the polluted periods of 2018 than in 2022 (1.8×10^-9/h), mainly due to increased production of RO₂ and HO₂ radicals from high concentrations of alkanes and aromatics. Additionally, the marked decline in TVOC concentrations during the polluted periods of 2022 suggests a shift in O₃ formation from a VOC-limited regime to a transitional regime, highlighting the need for joint control of TVOCs and NO_x. The results of VOCs emission reduction indicated that O₃ was most sensitive to reductions in the top 10 OFP-contributing species, with relative incremental reactivities (RIR) of 0.85%/% in 2018 and 0.81%/% in 2022, which was more effective than reducing alkenes (0.74%/% in 2018 and 0.37%/% in 2022), aromatics (0.44%/% in 2018and 0.49%/% in 2022), and the top 10species with the highest concentrations (0.20%/% in 2018and 0.37%/% in 2022).