In this research, a gene named NtACOY2 encoding a novel ACC Oxidase ( ACO ) protein was isolated using RTPCR from ‘Yunxiang’ (Narcissus tazetta var. ‘Yunxiang’). The full length cDNA of NtACOY2 consisted of an open reading frame (ORF ) of 936 bp, and encoded a 35.83 kD protein with 311 amino acids. Bioinformatics analysis indicated that NtACOY2 contained a typical DIOX_N and 20GFeⅡ_Oxy binding domain. Evolutionary analysis indicated that the amino acid sequence encoded by NtACOY2 was highly conserved. Realtime fluorescence quantitativePCR results revealed that the expression of NtACOY2 in the petal and deputy crown is increasing with the senescence of ‘Yunxiang’. The expression of NtACOY2 in petals in each period was higher than that in the deputy crown, and the highest expression in petals is at bud stage. So it is inferred that NtACOY2 may be involved in the development of ‘Yunxiang’ and related to flower senescence. The expression vector of NtACOY2 was successfully constructed by PCR and identified by restriction enzyme digestion reactions. And the sense plant express vector of NtACOY2 was used to transform the tobacco through Agrobacteriummediated procedure. PCR detection showed that a total of 15 transformed plants were amplified fragments with the same size as the positive controls. The result of RTPCR identification showed that 12 transgenic tobacco plants were obtained. Two randomly selected transgenic plants (Z1, Z2) and wild type (WT) exactly the same condition of transplanting under greenhouse cultivation, the results showed that the flowering time of Z1, Z2 were 8 d and 7 d earlier flowering compared with control plants, and the flower number of transgenic tobacco were more than the wild type, it is showed that NtACOY2 could normally expressed at the transcriptional level. The experimental results laid the foundation for further research on the function of NtACOY2 gene.