Abstract: Cytokinin oxidase could degrade cytokinins, and thus influence various aspects of plant growth and development. ZmCKX gene function could be understood from ZmCKX gene cloning, which can provide the basis for maize's resistance reaction. Prokaryotic expression vector of ZmCKX gene was constructed and was expressed. ZmCKX full length cDNA was cloned by using RT-PCR and RACE technique, and preliminary analysis of the bioinformatics was carried out on it. A pair of primers was designed according to digestion sites in plasmid pMD- 19t and the ZmCKX gene sequence by GenBank. The DNA fragment of 1035 bp was amplified by PCR from the pMD-ZmCKX recombinant plasmid with ZmCKX gene, then cloned into pMD-19t and transformed into the host E.coli strain DH5α. The fragment was conformed to the original sequence. It indicated that fusion expression vector pMD- ZmCKX was constructed. The pMD- ZmCKX plasmid was transformed into DH5α for expression. The expression product of ZmCKX gene was identified by AGE (agarose gel electrophoresis). The open reading frame of ZmCKX was 1035 bp in length and encoded a predicted protein of 344 amino acids. The analysis of cDNA sequence shows that ZmCKX shares 99% identity with ZmCKX1. ZmCKX genes encoding protein exists in the cytoplasm, and ZmCKX is hydrophilic protein.