The consensus sequence of Le1 515 bp in soybean seeds was cloned in this study by RT-PCR.A RNAi expression vector was constructed on the substructure of the plant expression vector pCAMBIA1301,that could inhibition the expression of Le1 gene.Restriction enzyme analysis and DNA sequencing showed that all the recombinant plasmids were according with our design.This study created the foundation for decreasing the activity of soybean agglutinin and improving the quality of soybeans by RNAi.