A series of caudatin ester derivatives were synthesized and tested for their activities against human lung cancer A549, human prostate cancer PC3, human liver cancer BEL-7402 and human gastric cancer SGC-7901 cell lines. All the compounds showed noticeable activities against the tested tumor cell lines, and the IC50s are all lower than that of caudatin. Among them, 5e and 5h are the most potent compounds. SAR study implies that introducing either a halogenated acyl group or amino aryl group to the C3β position of caudatin is beneficial to their anti-viability activities, and the lipophilicity affects the anti-viability activity of caudatin derivatives.