Caleosin are a class of calcium-binding proteins embedded in the phospholipid monolayer of lipid droplets. In addition to maintaining thestructure of lipid droplets, caleosin proteins areinvolved in dormancy and lipid signaling, and areassociatedwith the stress response via their histidine-dependent peroxygenase activity. To date, caleosins have been studied in Arabidopsis thaliana. However, little is known about these genes in legumes,including the most cultivated oilseed crop, soybean. In this paper,20 caleosin genes in soybean, common bean and barrel medic werestudied. Among these, 13 caleosin genes, including 3 in Glycine max, 5 in Phaseolus vulgarisand 5 in Medicago truncatula, are identified for the first time. The structures, characteristics and evolution of the 20 caleosin proteins are analyzed. Expansion patterns show that tandem duplication was the main reason for the caleosin family expansion in the legume. Expression profiles indicate that L-caleosin in soybean and common bean are more important than H-caleosin, which is just the opposite in Arabidopsis thaliana. GmaCLO2, PvuCLO1, PvuCLO3and MtrCLO3may play important roles, while GmaCLO6, GmaCLO10and MtrCLO4may lose their function in the examined tissues. In addition, according to the results of cis-element analyses, we propose potential functions for the more important caleosin genes in leguminous plants. Our work provides helpful information for further evolution and function analyses of the caleosin gene family in soybean, common bean and barrel medic.