Abstract sInterspecific hybridization is widely observed within diverse eukaryotic taxa and is considered an important driver of genome evolution. We selected one flowering Chinese cabbage variety and one broccoli variety for hybridization. Heterologous haploid offspring were obtained by embryo rescue, and heterologous diploids were obtained by colchicine-induced chromosomal doubling. The field traits and simple sequence repeat markers of 124 F2 plants were investigated. We also analyzed the nutritional components of the parental and 10 progeny F2 plants. The parental traits were separated in the hybrids, with traits tending to shift from those of flowering Chinese cabbage to those of broccoli, and trait values showed normal distributions. Simple sequence repeat patterns varied, with the number of missing bands being significantly greater than that of novel bands in hybrids. Additionally, there were higher levels of some nutritional components in the hybrids compared with in the parents. Thus, the phenotypes of the early formed allopolyploids were unstable and accompanied by dramatic changes in the genome. Hybrids showed new traits and high levels of nutritional components. This study not only increased the genetic resources available for flowering Chinese cabbage but also laid a theoretical foundation for exploring trait segregation in early formed allopolyploids.