Abstract: Some kinds of VOC from natural sources can react with oxidants such as ozone in the atmosphere. The products enter the particle phase through the physical process of condensation, nucleation or gas-particle partition and form secondary organic aerosols (SOA). The low-temperature matrix isolation system and temperature programmed technique were combined to study the transient species from the reaction of α-pinene with ozone. The temperature was changed from 6 K to the ambient temperature, during which FT-IR was used to detect the intermediate products. The results showed that two important products, the primary ozonide (POZ) and the secondary ozonide (SOZ), were observed successfully. The infrared absorption characteristic bands of POZ appeared at 699 and 998 cm^-1, corresponding to OOO antisymmetric stretching vibration and the coupling of C—O stretching vibration and CH₂ rocking vibration, which was consistent with the theoretical calculation results. The infrared absorption characteristic bands of SOZ appeared at 960 and 1205 cm^-1, corresponding to methyl bending vibration and OCO bending vibration, which also agreed with the theoretical calculations. The ab initio B3LYP method showed very good performance in predicting the characteristic vibrational frequencies and agreed well with the experimental data. Configuration of POZ and SOZ were output using B3LYP, and they all possessed asymmetric conformation. Contrasting this reaction with that of ethylene, propylene or cyclopentene with ozone, we found that POZ of these reactions had a steady O-envelop conformation, and SOZ had an OO half chair conformation. However, CI of α-pinene was not detected. High energy state CI was unstable, and the cold head heat conduction effect was not good, so that the peaks of CI were not detected by FT-IR. The study lays an experimental and theoretical foundation for the research of structure of precursor and formation process of SOA.