Abstract: Due to intense emissions, complex terrain, and unique meteorological conditions, the Sichuan Basin has experienced severe ozone (O₃) pollution in recent years. In this study, the Thiel-Sen estimator, random forest modeling, and meteorological normalization technique were used to analyze the spatiotemporal patterns and underlying mechanisms of regional surface O₃ concentrations using monitoring data and corresponding meteorological observations from May to September during 2019-2024. Spatially, the hourly and daily minimum O₃ concentrations were highest in southern Sichuan, followed by the Chengdu Plain and northeastern Sichuan. In contrast, maximum daily 8-hour average (MDA8) and daytime O₃ concentrations peaked in the Chengdu Plain, indicating stronger local photochemical production in this region. O₃ concentrations levels showed significant increasing trends from May to September during 2019-2024, with southern Sichuan experiencing the fastest annual growth (hourly O₃ concentrations was 3.3 μg/m³, MDA8 O₃ concentrations was 3.6 μg/m³). Diurnal variations consistently followed a unimodal peak-trough pattern across all subregions, with peak concentration growth rates significantly surpassing nighttime rates, highlighting enhanced photochemical efficiency as the dominant driver. Meteorological contributions (71.4%-80.0%) outweighed emission contributions (20.0%-28.6%) in influencing O₃ concentrations trends, with relative humidity, temperature, mixing layer height, and downward surface solar radiation identified as the key meteorological factors. After meteorological normalization, the annual growth rate of hourly O₃ concentrations (0.9-1.5 μg/m³) was substantially lower than the observed rate (2.8-3.3 μg/m³), underscoring the amplifying influence of meteorological conditions, particularly under post-2022 high-temperature and low-humidity conditions. These findings suggest that O₃ control strategies should prioritize mitigating pollution episodes that arise under such synergistic meteorological conditions.