Abstract: To study the changes in the hypocotyls and quizzing cotyledon differentiated and plant regeneration frequency under different concentrations of hormone combinations, hypocotyls and cotyledons with petiole of Brassica napus L.（wild-oil 19）were taken as explants. The results showed that, after pre-cultured for 4 days using 1.5 mg/L 2, 4-D and transferred to differentiated medium of hypocotyls and cotyledons with Petiole, the derived callus initiated earlier and developed faster with a higher induced frequency. Among them, the hypocotyls transferred to the MS +3 mg/L 6-BA +0.1 mg/L NAA as differentiated medium reached the highest regeneration frequency of 86.67% ；However, the regeneration frequency of cotyledon explants was much lower than hypocotyls with a final regernation frequency of 46.67% using MS with 4 mg/L 6-BA and 0.3 mg/L NAA as differentiated medium. In this study, the high frequency regeneration system of Brassica napus L.（wild-oil 19）was established.

Key words: Brassica napus L., Hypocotyl, Cotyledons with petiole, Regeneration frequency, Differentiation frequency