A MADS-box gene was isolated from the petal of Sedirea japonica by using RT-PCR and RACE approaches and the gene was named AP1-like（The accession number in GenBank：JQ776636）.The full length cDNA of AP1-like is 1 221 bp,with an ORF of 753 bp encoding 250 putative amino acid residues.Multiple sequence alignment and phylogenetic tree analyses showed that AP1-like is close to ORAP11 from Phalaenopsis amabilis with an 96% sequence similarity.This protein is hydrophilic and contains 53.60% α-helical domains,7.20% extended strand,39.20% random coil.The expression was analyzed by real-time fluorescent quantitative PCR and this gene was expressed in different parts in different periods,but expression abundance was different.In roots and leaves,the highest amount of expression was observed during full-bloom stage,In the reproductive organs,the highest expression level of AP1-like was detected in scapes,followed by in buds during the bud period.The expression level of AP1-like in scapes showed higher than that in ovaries and columns during full-bloom period.The expression of AP1-like in sepals and petals and lips showed the lowest level.The results showed that this gene may play an important role in regulating the transition from vegetative growth to reproductive growth and the ovary development.