Exploring the Oleosin gene family in Cyperus esculentus and identifying key family members in oil storage are crucial for deciphering the regulatory mechanisms of oil accumulation. In this study， we conducted a comprehensive analysis of the Oleosin gene family members in Cyperus esculentus and other species using bioinformatics methods. The tissue-specific expression analysis of CeOLEs and functional verification were further carried out. Genome-wide analysis revealed six Oleosin gene family members （CeOLE1-6） in Cyperus esculentus， phylogenetically classified into three evolutionary lineages： U， SL and SH. These genes exhibited high expression levels in the tubers， but extremely low expression in roots， leaves， tillering nodes， stolons and other tissues. The expression pattern correlated strongly with the observed oil content， where tubers accumulated up to 24.68% oil content， while other tissues contained less than 1.00% oil content. Moreover， we found that CeOLE1， CeOLE2， CeOLE3 and CeOLE5 had higher expression levels， and their expression patterns were consistent with the rate of oil content changes in tubers （initially increased and then decreasing）. This indicates that these four genes may play pivotal roles in regulating oil accumulation in Cyperus esculentus tubers. Overexpression of CeOLE1， CeOLE2， CeOLE3 and CeOLE5 in Arabidopsis resulted in significantly increased seed oil content， thereby confirming the role of these four CeOLEs in oil storage.