One thousand five hundred rapeseed accessions were collected from gene banks in several countries and surveyed for their seed traits such as oil content, protein content, fatty acid composition and seed weight. Seed chemicals were analyzed by near-infrared reflectance spectroscopy (NIRS). An extensive genetic variation existed among accessions for all seed traits examined. The oil content ranged from 24.7 to 56.9%, and the protein content ranged from 6.7 to 36.6%. A hundred seed weight ranged from 0.13 to 0.70 g. The fatty acid compositions of germplasms also varied from 2.6 to 9.2% of C16:0 (palmitic acid), 0.3 to 70.2% of C18:1 (oleic), 10.3 to 28.9% of C18:2 (linoleic), 4.8 to 15.3% of C18:3 (linolenic), 0 to 10.5% of C20:1(eicosenoic) and 0 to 59.6% of C22:1 (erucic). The oil content had strong negative correlation with protein content (r = −0.848). However, it did not have any close correlations with other traits. When the genetic stability of seed traits was examined by comparison between original seeds and self-pollinated seeds (S 1 seeds), higher positive and significant correlation coefficients between original seeds and S 1 seeds were found in all seed traits.