Abstract: Cinnamyl alcohol dehydrogenase (CAD, EC1.1.1.195) is a key enzyme in the lignin biosynthesis pathway. By using NADPH as a cofactor, CAD catalyzes cinnamyl aldehydes to alcohols and plays an important role in plant development and stress responses. This study identified 16 CAD genes in Zoysia japonica. Phylogenetic and structural analyses of these genes were conducted. Semi-quantitative RT-PCR indicated that 5 ZjCAD genes were specifically expressed in leaves. Lignin histochemical staining and expression analyses of ZjCAD genes in different cultivars and a wild accession further showed that the expression pattern of ZjCAD6 was positively correlated with leaf lignin contents. These results indicate that ZjCAD6 may be the key gene that regulates lignin biosynthesis in the leaves of Z. japonica. The full length of the ZjCAD6 gene is 2736 bp, and is comprised of three introns and four exons. The 1074 bp open reading frame of ZjCAD6 encodes 357 amino acids. ZjCAD6 protein contains two Zn²⁺-binding motifs and a NADP(H)-binding motif, which is vital for its catalytic activity. Our results provide an important reference for further study of both lignin content's molecular mechanisms and the tensile strength of Z. japonica leaves.