A MADSbox gene, NtPI2, was cloned from the flower bud of Narcissus tazetta var. chinensis using RTPCR and rapid amplification of cDNA ends. NtPI2 is 810 bp in length with an open reading frame 627 bp which encoded 208 amino acids. Phylogenetic analysis indicated that NtPI2 belongs to the PI/GLO family. Realtime quantitative PCR demonstrated that NtPI2 was expressed in all tissues of ‘Jinzhanyintai’. The expression pattern of NtPI2 was different in different organs of flower in single and double narcissus. We compared the expression pattern of NtPI2 in single and double narcissus, and found that the expression of the NtPI2 of the stamen petaloids and corona in double narcissus ‘Yulinglong’ were significantly higher than that of in single narcissus ‘Jinzhanyintai’. This indicates that the increased expression of NtPI2 in the petaloid stamens may be the direct cause of the occurrence of the double narcissus. Plant express vector of NtPI2, pCAMBIA1302NtPI2, was constructed and used to transform the tobacco through Agrobacteriummediated procedure. The result of molecular identification showed that 8 transgenic tobacco plants were obtained. The results will lay a foundation for the further study of the NtPI2 gene function and its relationship with the formation of the double narcissus.