Abstract: To investigated the chemical constituents of the roots of Psidium guajava,we isolated seven compounds by silica gel column chromatography.These include oleanane derivatives,2 α,3β,6β,23-tetrahydroxylurs-12,20(30)-dien-28-oic acid β-D-glucopyranoside (1),2α,3β,6β,23-tetrahydroxylurs-12,18-dien-28-oic acid β-D-glucopyranoside (2),2α,3β,23-trihydroxylurs-12,18-dien-28-oic acid β-D-glucopyranoside (3), nigaichigoside F1(4),asiaticoside C (5),2α,3β,6β,19α,23-pentahydroxylurs-12,18-dien-28-oic acid β-Dglucopyranoside (6) and 2α,3β,19α,23-tetrahydroxylurs-12-en-28-oic acid (7).Their structures were elucidated on the basis of spectral analysis with reference to the published data.Compound 1 is brand new,compounds 2-6 were first isolated from this plant.The new compound was evaluated for their cytotoxic activity against human hepatoma Bel 7402 in vitro.The results were expressed as the ratio of inhibiting Bel 7402 cells growth by comparing to untreated cells.The new compound (concentration:25 μmol·L^-1) showed the ratio values of 52.5%.