Abstract: Codeine-O-demethylase (CODM) is a key enzyme in the biosynthesis of codeine and morphine. In this study, CODM gene sequences were cloned from Papaver somniferum and Papaver rhoeas, and were compared with each other by sequence alignment and bioinformatics analysis. The results showed that there were three genotypes of CODM in Papaver somniferum and five genotypes of CODM in Papaver rhoeas. Bioinformatics analysis showed that all CODM proteins had no signal peptide sequence, and these proteins were predicted to be non-secretory proteins, belonging to the Pcbc supergene family. Although the amino acid sequences of CODM in poppies are the same, the expression levels of CODM in different poppy resources are significantly different. It is speculated that the variation of transcription level of CODM may be related to its non-coding region sequence, which lays a foundation for further research on the synthesis and regulation mechanism of alkaloids in poppies.