Terpene synthase (TPS) gene is a key gene in the biosynthesis pathway of terpenoids, playing a crucial role in plant terpene metabolism. In this study, the floral fragrance components of lilac petals in different flower development stages were identified and analyzed on the basis of optimizing the floral conditions of headspace solid-phase microextraction (HS-SPME) . The key candidate genes of SoTPS2 and SoTPS3 were selected by combining genome and transcriptome data, and their cloning and functional study were carried out. The results show that: (1) The optimal extraction condition was 30 ℃ for 40 min by analyzing the difference of types and release amount of volatile compounds under different extraction temperature and time; The total release of floral fragrance showed a trend of first increasing and then decreasing during the four flower development stages, reaching the highest level at full flowering stage; Terpenes accounted for the highest proportion in the four periods, and monoterpene Ocimene released the highest amount. (2) The ORF of SoTPS2 and SoTPS3 genes was 731 and 1779 bp respectively, encoding 576 and 592 amino acids, and the encoded protein has Terpene_Cyclase_Plant_C1 conservative structural domain, belonging to Isoprenoid_ Biosyn_ C1 superfamily; The real-time PCR results showed that the expression of the two genes was the highest in the petals, with an increasing and then decreasing trend at different flower development stages, which was positively correlated with the release of ocimene. (3) The heterologous transient overexpression of SoTPS2 and SoTPS3 genes in the petals of Antirrhinum majus showed that the release of Ocimene was significantly increased by 10.91 and 23.67 times, respectively. In conclusion, the main the floral fragrance components of lilac petals are monoterpenes, with SoTPS2 and SoTPS3 as pathway downstream genes having a large effect on monoterpenes, especially ocimene.