Abstract: To investigate the pollution characteristics and formation mechanisms of carbonyl compounds in Jinan City during summer, this study conducted atmospheric observations in a typical residential area in June 2022, combined with an observation-based model (OBM) to analyze their sources and photochemical pathways. Results showed that the average concentration of carbonyl compounds was (12.08±4.26)×10⁻⁹, dominated by formaldehyde (5.33±2.23)×10⁻⁹, acetaldehyde (4.08±1.00) ×10⁻⁹, and acetone (1.59±0.51)×10⁻⁹, accounting for 44.12%, 33.77%, and 13.16%, respectively. Diurnal variations exhibited a tri-modal pattern: morning peaks (vehicle emissions), afternoon peaks (photochemical processes), and nighttime peaks (diesel vehicle and barbecue emissions), driven by anthropogenic activities and meteorological conditions. Model simulations revealed a net formaldehyde formation rate of 0.23×10⁻⁹-0.94×10⁻⁹ h⁻¹, with significant contributions from alkanes and alkenes (highest Relative Incremental Reactivity, RIR=3.3), while acetaldehyde showed net consumption due to intense photochemical reactions. Sensitivity experiments demonstrated that controlling alkane and alkene emissions could effectively reduce formaldehyde and acetaldehyde concentrations.