Abstract: The seed proteins from 20 species(or varieties) of genus Brassica plants were determind and their fatty acid compositions in the seed oils were analysed by gas liquid chromatography. The seeds of genus Brassica plants studied contain 21.2—28.8% protein and 29.3—43.2% oil on dry base. All the seed oils of the plants contain same 14 fatty acid components, among them characteristic fatty acid is the erucic acid which makes up 24.2—52.0% of the seed oils. The other major fatty acids are oleic acid (8.4—20.6%), linoleic acid(8.8—20.4%), linolenic acid (5.2—12.5%) and gadoleic acid(4.4—11.7%). Contents of the proteins and fatty acid components in the different species of Brassica are different, but those in B. norinosa are similar to those in B. chinensis, This results support the view of Tsen et Lee who regard B. norinosa as a variety, B. chinensis var. rosularis, not a real species of Brassica.