OBJECTIVE： To synthesize and identify rotundic acid esters derivatives， and to evaluate in vitro antitumor activity. METHODS： Using rotundic acid as raw material， rotundic acid esters derivatives were synthesized by 28-esterification， 3β and 23-position hydroxyl group combined with acid anhydride. The structure of rotundic acid esters derivatives were identified by HRMS， 1H-NMR， 13C-NMR and physicochemical properties. The in vitro antitumor activities were evaluated by MTT assay against paclitaxel （positive control）， rotundic acid and rotundic acid esters derivatives with human cervical cancer cells HeLa， human malignant melanoma cells A375， human lung adenocarcinoma cells SPC-A1 and human liver cancer cells HepG2 （take IC50 as an indicator）. RESULTS： Totally 6 kinds of rotundic acid esters derivatives were synthesized， i.e. rotundic acid methyl ester（compound 1）， 3， 23-O-di（acetyl） rotundic acid methyl ester（compound 2）， 3， 23-O-di（propionyl） rotundic acid methyl ester（compound 3）， 3， 23-O-di（butyryl） rotundic acid methyl ester（compound 4）， 3， 23-O-di（phthaloyl） rotundic acid methyl ester（compound 5） and 3， 23-O-di（succinyl） rotundic acid methyl ester（compound 6）. Compared with paclitaxel， the antitumor activity of compound 5 and compound 6 to Hela， A375， HepG2 and SPC-A1 was similar to it， and there was no significant difference between them （P＞0.05）； the IC50 of rotuntic acid and other compounds decreased with statistical significance （P＜0.05）. CONCLUSIONS： In the study， 6 kinds of rotundic acid esters derivatives are synthesized and compound 5 and compound 6 have significant antitumor activity in vitro， which can provide reference for further study.