Abstract: Orchid species show variable biological characters and important commodity characteristics. Phalaenopsis equestris is the first species in Orchidaceae whose wholegenome sequencing has been finished. Its essential to mine important gene families in Phalaenopsis equestris for genomics research of orchidaceae. In this paper， NCBI blast search was adopted to identify NAC transcription factors in Phalaenopsis equestris， and then phylogenetic relationships， conserved domain and gene structure analysis of these genes were performed. After removing redundant and mismatch sequences， 86 genes in Phalaenopsis equestris were identified as PeNACs， all of which contained a typical NAM domain. Two of them （PEQU_23244 and PEQU_40419）， predicted to have a transmembrane motif in Cterminal sequence， belonged to MTFs （membranebound transcription factors）. Sixteen of all 86 PeNACs only contained parts of the consensus sequence for NAM domain. The rest 70 PeNACs were used to construct phylogenetic tree with AtNACs. According to phylogenetic analysis， all these genes could be divided into A and B two major groups， and each of them were further classified into 3 and 12 subfamilies. The gene and protein structure of PeNACs were more diverse in group A than in group B. Members of NAM subfamily in PeNACs were highly homologous with Arabidopsis CUC1， CUC2 and CUC3.

Key words:  NAC transcription factor, Phalaenopsis equestris, sequence identification, phylogenetic analysis