Abstract: Meconopsis horridula is an important traditional Tibetan folk medicine.The plant has function of clearing internal heat and promoting blood circulation for removing blood stasis.It was used to treat fractures and bruises.Many alkaloids have been isolated from this species,most of which have significant bioactivities.In this study,the 95% alcohol extract from the aerial part of Meconopsis horridula was fractionated using open column chromatography with silica gel and ODS.Three alkaloids were isolated from the plant.A new proaorphine alkaloid,(6a-S)-des-N-methyl-(+)-cryprochine(1),together with two known alkaloids,cheilanthifoline(2) and protopine(3) were isolated and identified.Compound 2 was isolated from this plant for the first time.The structures of purified compounds were determined using spectroscopic methods including IR,MS,and 1D and 2D NMR,and by comparison with literature data for known alkaloids.