Abstract: An alkali-saline mixed stress was used to simulate the effect of salt-alkalinized soil on the germination rate, germination index, seeding height, and root length of Flaveria bidentis. Simultaneously, the effects of the stress on antioxidant enzyme (SOD, POD, CAT) activities, chlorophyll content, and MDA (malondialdehyde) were investigated. The features of salt-alkalinized soil in Hebei were simulated using 24 different alkali-saline conditions with salinities and pH obtained by mixing two neutral salts (NaCl and Na₂SO₄) and two alkaline salts (NaHCO₃ and Na₂CO₃) in various proportions. There was a negative effect of salt on the germination rate, germination vigor, seeding height, and root lengths of four groups; A, B, C, and D. At the same alkalinity, the germination rate, germination vigor, seeding height, and root length of all treatments increased significantly with reduced alkalinity. Statistical analysis showed that salinity was the dominant stress factor to inhibit seed germination and seedling growth of F. bidentis, while other indices, such as pH, had no decisive effect on germination. After saline-alkali stress, the relative rate of chlorophyll destruction, membrane permeability, and MDA of the F. bidentis leaves increased. In the early stages of saline-alkali stress, SOD and POD activity increased, but CAT activity was not significantly different from the control. This showed that F. bidentis leaves mainly rely on SOD and POD activity to temporarily maintain the dynamic equilibrium of reactive oxygen generation and scavenging.