Abstract: The petal spur of Calanthe triplicata at different development stages was used as the test materials.Two genes that expressed differentially during the auxin signal transduction pathway, namely CtARF57 and CtIAA12,were cloned from petal spur of Calanthe triplicata based on transcriptome data and analyzed by bioinformatics, in order to investigate the expression characteristics and functions of auxin related response factors（ARF and Aux/IAA） in Calanthe triplicata,and to reveal the development mechanism of petal spur.The results showed that the full length of cDNA were 3 054 bp and 1 124 bp, encoding 911 and 177 amino acids, respectively.Homology analysis showed that the amino acid sequences of the two genes had high homology similarity with Dendrobium catenatum,and the similarity was more than 84%.Conserved domain analysis showed that CtARF57 protein had B3 domain, Auxin＿resp domain and Aux/IAA domain; CtIAA12 contained the typical Aux/IAA protein DomainⅠ,Ⅱ,Ⅲ and Ⅳ.The results of real-time fluorescence quantitative PCR showed that the transcriptional level was induced by auxin, and the expressions of the two genes were significantly different at different stages.The expression levels of the genes were the highest at the last stage of petal spur development, and were lower in the first and second periods, which was consistent with the trend of FPKM value of the transcriptomic.The above results preliminarily suggested that two response factor genes were involved in the auxin signal transduction pathway to regulate the morphogenesis, growth and metabolism of Calanthe triplicata in petal spur of the garden flower.