The Dof proteins belong to a large family of plant transcription factors that share a single highly conserved zinc finger and play an important role in many physiological processes. To elucidate the function of Dof in soybean, GmDof17-1 was cloned from soybean (Glycine max (L.) Merr); the open reading frame (ORF) of GmDof17-1 is 846 bp and encodes a putative protein that includes 281 amino acids. Using qRT-PCR, the expression profiles of GmDof17-1 were obtained for various parts of the soybean plant. GmDof17-1 was primarily expressed in the roots and pods at various stages of pod development. The gene was ectopically expressed in tobacco under the control of the 2 × CaMV35S promoter to study the functions of the gene product. The transgenic tobacco plants showed to be dwarf, and the indole-3-acetic acid (IAA) content was decreased, whereas the sulfur-containing amino acid content of the seeds increased. These results provide new insight into the function of GmDof17-1 in seed development.