This study adopts MAX-DOAS technology and optimal estimation methods to analyze the vertical profiles of aerosols, HONO, and O₃ in Kunming during winter 2024, thereby clarifying their vertical distribution characteristics and diurnal variation rules. Aerosols are predominantly concentrated in the near-surface layer, with concentrations decreasing gradually with increasing altitude; their concentrations rise in the morning, reach a peak at 10 a.m., and then decline, with the maximum extinction coefficient reaching 1.3 km⁻¹. HONO concentrations decrease exponentially with height, being the highest around sunrise, the lowest at noon, and then gradually accumulating, with the maximum concentration exceeding 3.14 × 10¹⁰ molec·cm⁻³. O₃ achieves its maximum concentration in the 2.6–4 km altitude range in the afternoon (the highest concentration > 1.16 × 10¹² molec·cm⁻³), while near-surface O₃ concentrations increase steadily from morning onward. Model analysis demonstrates that without considering HONO, OH radicals shift from net production to net loss in the morning, leading to reduced O₃ production rates and a decrease of approximately 8 ppb in the maximum O₃ concentration. These findings highlight the significant vertical and diurnal variations in the three pollutants, emphasize HONO’s crucial role in OH radical generation and O₃ formation, provide valuable scientific support for air pollution control, and confirm HONO’s important impact on regional atmospheric chemistry and the distribution of key pollutants.