In the sexual intergenerie hybrids between the cultivated Brassica species and Orychophragmus violaceus, both complete separation and partial separation of the parental genomes were found to occur during mitosis and meiosis under genetic control. The cytogenetics of these hybrids was species-specific for Brassica parents. The different chromosome behavior of hybrids with three Brassica diploids (B. camtpestris, B. nigra and B. oleracea) might contribute to the different cytogenetics of hybrids with three tetraploids (B. napus, B. juncea and B. carinata). Owing to the parental genome separation, Brassica homozygous plants and aneuploids with various chromosome constitutions were identifiable in the progenies of these hybrids, which were valuable for the study of the structure and evolution of Brassica genome and for the breeding of Brassica crops.