Two new resorcinol derivatives 2-methoxy-4-hydroxy-6-(8Z-pentadecenyl)-benzene-1-O-acetate (1) and 2-methoxy-4-hydroxy-6-pentadecyl-benzene-1-O-acetate (2), together with four known compounds 2-methoxy-4-hydroxy-6-tridecyl-benzene-1-O-acetate (ardisiphenol D, 3), 5-(8Z-pentadecenyl)resorcinol (4), 5-pentadecylresorcinol (5), 5-tridecylresorcinol (6), have been isolated from the roots of Ardisia brevicaulis in our previous work. In the present study, the inhibitory effect of 1–6 on the proliferation of human pancreatic PANC-1, human lung A549, human gastrointestinal carcinoma SGC 7901, human breast MCF-7, and human prostate PC-3 cancer cells was evaluated by the methyl thiazolyl tetrazolium method. Compounds 1–6 all showed inhibitory activities against the proliferation of PANC-1, A549, SGC7901, MCF-7, and PC-3 cancer cells. Compound 3, the most active agent and the main constituent with the highest yield, induced apoptosis of PANC-1 cells (the most sensitive cell line among the cell lines screened) via the activation of caspase-3 and caspase-9, up-regulation of the ratio of bax/bcl-2 protein expression.