Abstract: The basic Helix-Loop-Hleix (bHLH) gene family, one of the largest plant transcript factor families, played an important role in the growth and development in plants and animals. The evolutionary mechanism of the soybean bHLH gene family was analyzed, further the function differentiation through bioinformatics and molecular biology methods was discussed. The results showed that the soybean contains 340 members of bHLH genes, which can be divided into 24 subgroups through the domain structures, motif compositions and phylogenetic relationships, and distributed in 20 chromosomes unevenly. The chemical characteristic of bHLH genes were significantly different with the length of amino acid was 91~815, the relative molecular weight was 10 273.88~91 300.38, and the theoretical equivalence point varies from 4.56 to 10.40. The alkaline amino acid region contains the conservative sequence of His5-Glu9-Arg13, which is associated with the target gene. The bHLH region contains Arg23 and Arg55 and contains five conservative elements, which is related to the formation of dimer. Most of the members showed specific tissue expression and different gene expression levels in root and the development of flower in soybean.