Abstract: The allelopathy of planting soil aqueous extract from Codonopsis pilosula and Astragalus membranaceus. var. mongolicus on Vicia faba was studied. The effect of different concentration (0.5000, 0.2500, 0.1250 and 0.0625 g/mL) of planting soil aqueous extract from C. pilosula and A. membranaceus. var. mongolicus on seed germination and seedling growth of V. faba was researched by bioassay method. The results showed that the increase of relative waterintake rate of V. faba in the course of seed imbibition could be inhibited by aqueous extract. The low concentration of planting soil aqueous extract from C. pilosula and A. membranaceus.var. mongolicus could promote the seed germination and seedling growth of V. faba, but the high concentration of planting soil aqueous extract from Codonopsis pilosula and A. membranaceus. var. mongolicus would inhibit the seed germination and seedling growth of V. faba. The content of dissolubility, malonaldehyde and Pro in the leaf increased with the increment of queous extract concentration. The allelopathy of planting soil aqueous on V. faba from strong to weak were C. pilosula+A. membranaceus. var. mongolicus>A. membranaceus.var. mongolicus>C.pilosula.