Abstract: Flax is an important economic crop for fiber and/or oil in China. An efficient flax plant regeneration system was established through optimization of basal medium, hormone combination, flax genotype and age of hypocotyl explants. The best medium for callus and adventitious shoot differentiation was YB1. Shoot induction rate of Baihua, Heiya NO.4, K6531, K7697,HI026, HI045, I039 and Aliyana was 98.50%, 98.50%, 56.50%, 42.47%, 54.40%, 0, 27.13%, and 97.30%, respectively, and mean shoot number per explant was 11.43, 9.33, 2.17, 0.77, 1.10, 0, 0.90, and 10.68, respectively. Hypocotyls taken from seedlings 7 to 10 days old showed the highest regeneration ability. RB5 medium was optimal for root formation of regenerated shoots, with 100% root induction and 15.3 roots per shoot. Kanamycin at 60 mg.L-1 inhibited callus and shoot induction completely; the effect of ampicillin and cefotaxime at the concentrations tested was not significant.