In the paper the research on utilization of three-line heterosis in good quality Brassica napus is described. Following that the three paren-tal lines with low erucic acid in B.napus were all successfully developed, the stable three line materials with both low erucic acid and low thiogluco-side were obtained.The existing B.napus hybrids with low erucic acid express significant heterosis in yield constituents such as the number of effective branches,pods per plant and seeds per pod. The research work has sh...