Abstract: In order to clarify the role of PnSS gene in regulating the terpenoid contents in tobacco, an overexpression vector of PnSS gene was constructed. Tobacco cultivar Basma 14 was transformed by the leaf disc method, and the tobacco plants with overexpression of PnSS gene were obtained. The contents (mass fractions) of aroma components in the transformed tobacco leaves were analyzed by HS-SPME-GC/MS. The results showed that: 1) The consistency between amino acid sequences of PnSS and homolog NtSS in tobacco were 81.9%. PnSS and NtSS contained squalene and phytoene synthase domains. 2) Overexpression of PnSS gene resulted in shorter tobacco plants and smaller leaves. Compared with roots and stalks, the relative expression level of PnSS gene in tobacco leaves was the highest. 3) Overexpression of PnSS gene increased the contents of 13 aroma components, including acetic acid, furfuryl alcohol, 4,6-dimethylpyrimidine, phenylacetaldehyde, 3,5-dimethylbenzaldehyde, diene nicotine, dihydroactinidiolide, 2-methylpyrazine, nonanoic acid, isovaleraldehyde, 2 methyl butyl aldehyde, cembrane and nicotine in tobacco leaves. The treatment decreased the contents of 7 aroma components, including 2,3-dihydro-3,5 dihydroxy-6-methyl-4(H)-pyran-4-one, 2,3-bipyridine, phytol, phenylethanol, neophydiene, benzaldehyde and mesmin. Therefore, the overexpression of PnSS gene inhibited the growth and development of tobacco plants and changed the contents of aroma components, such as terpenoids, in tobacco leaves.