Abstract:The flower is the main reproductive organs of the plants, plays an extremely important role in the process of breeding and the PISTILLATA(PI) gene, and as a member of the B functional gene, plays an important role in floral organ development. In order to explore the function of PI gene in the development of petals and stamens, the PI gene in Arabidopsis thaliana was used as the research object, and the AtPI gene was amplified from cDNA by PCR, and the plant expression vector(pROKⅡ-AtPI) was constructed and transformed into tobacco. By PCR, the AtPI gene was integrated into the tobacco genome. The T2 generation plants were detected by qRT-PCR, and AtPI was also expressed at the level of mRNA. Transgenic tobacco plants exist obvious phenotype compared to wild-type tobacco, such as smaller corolla, shorter stamens, and abnormal ovary, which is 5-10 mm longer than wild-type tobacco. The specific participation in the development of stamens, petals and ovary meanwhile plays a crucial role is gene AtPI.