Abstract: mannosidases (Man), one group of glycosidases, have been universally distributed among most types of living organisms. Based on the published database of melon (Cucumis melo), we found the -Man family genes containing complete Glyco_hydro_47 or Glyco_hydro_38 domain. These protein sequences were analyzed by multi-sequence aligned, which are similar in Arabidopsis thaliana, Glycine max, Solanum lycopersicum, Theobroma cacao, Vitis vinifera, C. sativus, S. tuberosum and Setaria italic. And the structure evolution relation and conserved motifs were researched by bioinformatics method. The results indicated that the melon genome containd 8 琢-Man genes divided into class I and class II or 5 subfamilies. This protein was highly conservative with domain in the same class. Moreover, most of them had the same motifs in same order. On the contrary, the members of different classes had less similarity each other. This study is helpful for cloning and clarifying the function of -Man genes in melon, and can provide the diverse reference of the function and evolution for -mannosidase gene family in other plants.