Abstract: Brassinolide (BR) pretreatment significantly promoted the increase of superoxide dismutase (SOD) activity, as well as the chlorophyll and protein contents, the decrease of malondialdehyde (MDA) content and the electrolyte leakage in seedlings of Pinus elliottii Engelm. treated with drought, low temperature (4-5°C, 12°C), salt(0. 4% NaCl), and acid (H2SO pH 3) stress, respectively. There was an obvious inverse correlation between SOD activity and MDA content. The suitable concentration of BR was 0. 5 or 1 ppm. The experimental results showed that BR could enhance the stress resistance of the seedlings.