The paper studied on compatibilities of three backcross generations between interspecific hybrid, which was from CMS Brassica camperstris ssp. Pekinensis × Brassica oleracea var. acephala, and inter varietal hybrid, which was from CMS B. oleracea var. capitata × B. oleracea var. acephala. The results showed that there was segregation between B. camperstris ssp. Pekinensis and B. oleracea var. acephala in BC2 with a low compatible index of 2.45, but it had been overcome step by step until BC4 with a high compatible index of 6.17. While, there were no segregations between B. oleracea and B. oleracea var. acephala in BC2, BC3 and BC4 with compatible indexes of 6.20、6.23 and 6.27, respectively. The compatibility of B. camperstris ssp. Pekinensis×B.oleracea var.acephala closed to B.oleracea var. capitata×B.oleracea var.acephala in BC4.