Disclosed is a cucurbitane-triterpenoid compound for activating estrogen receptor activity, and a pharmaceutical composition, use and preparation method thereof. The cucurbitane-triterpenoid compound is presented as formula (I):wherein a single bond or a double bond is formed between C5 and C10, and a single bond or a double bond is fromed between C8 and C9； when a single bond is formed between C5 and C10, the R1 is oxygen； while a single bond is formed between C8 and C9, R2 is carbonyl group (—C═O), methyl hydroxyl group (—CH(OH)), methyl ketone or methyl dimethoxy group (—CH(OCH3)2)； and wherein while R1 is oxygen (—O—) and R2 is carbonyl group (—C═O) or methyl hydroxyl group (—CH(OH)), a single bond is formed between R1 (—O—) and C19 of R2 such that R1 and R2 are formed tetrahydro-2H-pyran-2-one or hemiacetal ring.
