Abstract: On the basis of the chemical structure of daidzein, a series of isoflavones have been synthesized. The intermediates, 7-methoxy-4'-hydroxyisoflavone(V) and 7-hydroxy-4'-methoxyisoflavone(Ⅸ) were prepared by condensation of corresponding desoxybenzoin with dimethylformamide dimethylacetal. 7-Methoxy-2-methyl-4'-hydroxyisoflavone (Ⅶ) was also prepared from desoxybenzoin Ⅳ by reacting with acetic anhydride and anhydrous sodium acetate and followed by hydrolysis.Compounds Ⅰ_1～5 were obtained by Mannich reaction and compounds Ⅱ_1,2 Ⅲ_1,2 were obtained by etherification of corresponding isoflavones.All compounds were tested for resistance to hypoxia in mice and Ⅰ_1～3, Ⅰ₅, Ⅱ₁ and Ⅲ₂ were shown to have significant effect. Compound Ⅰ₁ and Ⅰ₅ were also found to increase coronary blood flow.