In the process of screening for anti-human acyl-CoA:cholesterol acyltransferase (hACAT) agents from plant resources, we found that the 80% methanolic extract of Rhus chinensis (R. chinensis) exhibited significant antioxidative and hACAT activities in rats. Two compounds were isolated as active principles from the ethyl acetate soluble fraction of the branches of R. chinensis. The structures of compounds 1 and 2 were determined as hydroxydammarenone and semialactone, respectively, by means of MS and NMR spectroscopic analysis. Compound 1 has been isolated from this plant for the first time. Compounds 1 and 2 showed inhibitory activities on both human ACAT1 with $IC_{50}$ values of 12.4, and $79.1;{mu}M$ and on human ACAT2 with $IC_{50}$ values of 30.5 and $76.9;{mu}M$, respectively. These results suggested that R. chinensis containing dammarane triterpenes 1 and 2 might be effective in the prevention and treatment of hypercholesterolemia or atherosclerosis via inhibitory effect on hACAT.