In this study, ‘Baguazhou Shuiqin’ and the purplepetiole mutant ‘Nanxuan Baguazhou Zishuiqin’ were used as plant materials. A gene encoding cinnamyl alcohol dehydrogenase（CAD） was cloned from the cDNA of ‘Nanxuan Baguazhou Zishuiqin’ by RTPCR method and designated as OjCAD. The OjCAD gene contained a fulllength open reading frame of 1 074 bp, which encoded 357 amino acids. The relative molecular mass and theoretical isoelectric point of OjCAD protein was 39 143.10 and 6.91, respectively. The protein encoded by OjCAD is a member of MDR superfamily. The protein belonged to hydrophobic protein and its tertiary structure included 7 αhelix and 17 βturn. Alignments and phylogeneticanalysis indicated that OjCAD was highly conserved and had the closest phylogenetic relationships with the CAD protein from Daucus carota. Quantitative realtime PCR analysis demonstrated that the relative expression levels of OjCAD gene in leaf blades and petioles of purple and nonpurple Oenanthe javanica were different. The relative expression levels of OjCAD gene in leaf blades were higher than that in petioles. The relative expression levels of OjCAD gene in ‘Baguazhou Shuiqin’ were higher than that in ‘Nanxuan Baguazhou Zishuiqin’. Those results provided a basis for further research on the lignin biosynthesis in O. javanica.