Abstract: Two GA metabolism related genes ga1 and ga2 were cloned by using homology-based method and RACE from three tobacco species to explore the role in which gibberellic acids (GA) play in tobacco growth and development. Based on sequence alignment, a phylogenetic tree was constructed. qRT-PCR was executed to detect the gene expression profiles in Nicotiana sylvestris and Nicotiana tabacum. The results showed that they were highly conserved in sequences in solanaceae plants and genes in N. tobacum might originate from Nicotiana tomentosiformis. qRT-PCR analysis showed that ga1 and ga2 were expressed in much higher levels in leaves of stage before stem elongation and in stem of the stem elongation stage than other tissues in N. sylvestris.