To study the chemical composition of Euphorbia royleana Boiss. and the brine shrimp lethal activity,15 compounds were isolated from the ethyl acetate extract of this plant by normal phase silica gel,sephadex LH-20 and semi-preparative high-performance liquid chromatography (HPLC).Their structures were identified by modern spectroscopic techniques as 5(6)-gluten-3α-ol(1),taraxerol(2),epitaraxerol(3),ursolic acid(4),oleanolic acid(5),1-hydroxy-3,7,8-trimethoxyxanthone(6),methylswertianin (7),quercetin(8),daucosterol(9),β-sitosterol(10),stigmasterol(11),vanillin(12),1-dodecanol(13),trans-phytol(14),1-[(12E,16E)-12,16-eicosadienoyl]-2-[(E,E)-7,11-octadecadienoyl]-3-stearoylglycerol(15).Compounds 1,3,4,5,6,7,12,13,14 and 15 were isolated from this plant for the first time.Through the brine shrimp lethal activity test,compound 4 showed strong brine shrimp lethal activity,LD₅₀ was 7.687 μM.