Selecting Polygala tenuifolia Willd. as the study object, we studied the effects of brassinolide in two ways (presoaking and seed dressing) with various concentrations (0-100 μmol·L^-1) on seed germination, seedling growth parameters, physiological and biochemical characteristics and lead content of P. tenuifolia by 3 mmol·L^-1 lead acetate solution to simulate lead stress. The results showed that: (1) the germination rate, germination potential, germination index, vigor index of P. tenuifolia seeds and germ length, fresh weight and dry weight of seedlings decreased significantly under Pb stress. EBL presoaking and seed dressing could effectively alleviate the lead stress of P. tenuifolia seeds and seedlings with different concentrations and had a dose effect; (2) Under lead stress, the contents of free proline, soluble sugar and soluble protein in seedling increased at first and then decreased with the increase of EBL concentration, the contents with 0.01 μmol·L^-1 EBL seed dressing were 1.99, 2.31 and 1.95 times of 0 μmol·L^-1 EBL treatment, respectively, the effect of seed dressing was more significant than that of seed soaking. (3) The contents of superoxide dismutase, ascorbate peroxidase, peroxidase and catalase increased at first and then decreased with the increase of EBL concentration under lead stress. The activities with presoaking and dressing seeds were the strongest at 0.01 μmol·L^-1 EBL concentration. (4) Under lead stress, membrane lipid peroxidation and hydrogen peroxide decreased first and then increased with the increase of EBL concentration, which was significantly different from CK (blank control). The activities with presoaked seeds and seed dressing were the lowest at 0.01 μmol·L^-1 concentration. (5) Under lead stress, the accumulation of Pb in seeds and seedling increased significantly, and the increase of lead content in the seeds of the seed dressing treatment was much greater than that in seed soaking treatment, while the increase of the lead content in the seedlings had no significant difference between the two treatments; The lead content in leadstressed seeds was significantly increased after 0.0001 μmol·L^-1 EBL presoaking treatment, and significantly decreased after 0.0001-1.0 μmol·L^-1 EBL seed dressing treatment. The lead content with seed dressing and seed soaking treatments were significantly increased, and both were the highest under 0.01 μmol·L^-1 EBL treatment. The results showed that lead stress caused damage to the antioxidant enzyme defense system, and seriously inhibited the seed germination and seedling growth of P. tenuifolia. The appropriate concentration of EBL can effectively alleviate the damage of peroxidation, enhance the ability of plants to resist lead stress and significantly promote seed germination and seedling growth. Thus better stress resistance is shown by regulating the content of osmotic regulatory substances and the activities of protective enzyme system in P. tenuifolia seedlings under lead stress, but significantly promotes the accumulation of lead in seedlings.