The chemical constituents of Stelleropsis tianschanica were separated and purified by column chromatography,and the structures were identified by spectra analysis combined with physical and chemical properties.Finally,a total of 15 compounds were isolated from 95% methanol extract of  S. tianschanica,including three diterpenoids compounds,four phenylpropanoids compounds,four phenolic acids compounds,and the other four compounds.The structures were identified as excoecariatoxin (1),12-hydroxydaphnetoxin (2),2,5-dimethoxybenzoquinone (3),rutamontine (4),scorpinone (5),dihydrosyringenin (6),N-(2-phenylethyl)acetamide (7),pinoresinol (8),matairesinol (9),vesiculosin (10),threo-8S-7-methoxysyringylglycerol (11),cyclo(D)-pro-(D)-leu (12),threo-3-(4-hydroxy-3,5-dimethoxyphenyl)-3-ethoxypropane-1,2-diol (13),(-)-syringaresinol (14),threo-1-(4-hydroxy-3-methoxyphenyl)-2-{4-［(E)-3-hydroxy-1-propenyl］-2-methoxyphenoxy}-1,3-propanediol (15).Compounds 1-7,12-15 are isolated from the Stelleropsis genus for the first time.In addition,cytotoxic effects of compounds 1-15 were screened on HGC-27 gastric cancer cell lines.The results showed that compounds 1,2,3 and 10 were in the range of 50 μmol/L had strong inhibitory activity,and the inhibition rates were 92.0%,86.8%,87.28% and 76.34%,respectively,and their IC₅₀ values were 14.06,15.23,17.28,27.1 μmol/L.