The invention discloses a euphorbia splendens extract. The structure formula of the euphorbia splendens extract is expressed as formula (I), wherein R1 and R2 are cyclized to form cyclohexene or phenyl; any one or more hydrogen groups on cyclohexene or phenyl are substituted by R4; R4 is selected from hydrogen, hydroxyl, carbonyl, C1-C5 alcohol group or C1-C5 alkyl; or R4 and carbon on cyclohexene or phenyl form carbonyl; R3 is hydrogen, hydroxyl or carbonyl. The euphorbia splendens extract provided by the invention has obvious inhibition effect on lytic replication split period of EBV, is relatively low in toxicity to host cells, has certain safety and can be used for preparing drugs for preventing and treating EBV infection. The formula (I) is shown in the description.