LEAFY COTYLEDON1 (LEC1) is a key regulator of seed maturation, which gives embryos the ability to withstand desiccation. In this study, a novel transcription factor that is homologous to LEC1 in soybean (Glycine max) was isolated from Dongnong 50 by homologous cloning and was named as GmLEC1-A (GenBank accession number: MF681785). Sequence analysis showed that GmLEC1-A contained conserved B regions, which were functional domains of H4 factor. The relative expression level of GmLEC1-A was the highest in seeds of the soybean cultivar Dongnong 50. To verify the function of GmLEC1-A, ectopic expression of Arabidopsis thaliana and over-expression of soybean plants were generated. In Arabidopsis, the expression of GmLEC1-A restored the tolerance of lec1 mutant to seed drying, indicating that GmLEC1-A was a functional homolog of LEC1, and it might regulate the maturation phase of seed development. In soybean, over-expression of GmLEC1-A caused slower growth and lower germination rates as compared to that of wild-type soybeans. Furthermore, over-expression of GmLEC1-A seemed to increase the level of endogenous abscisic acid (ABA) at the germination stage. These results suggested that GmLEC1-A had a function in regulating ABA content at the germination stage.