Abstract: ELF3, an indispensable component of the circadian clock, plays an important role in plant growth and development. Soybean, a photoperiod-sensitive short-day crop, contains five ELF3 homolog genes. Of them, GmELF3 a/J is a key gene controlling the juvenility and leading to the green revolution in soybean. In order to analyze the function of the other four GmELF3 homologs, and to study the functional differences and genetic molecular mechanism of GmELF3 in depth, we preformed bioinformatical analysis with MEGA-X, Multalin SOPMA, ExPASy-Prot Param and so on to predict the phylogenetics, protein function, protein property, subcelluar location and gene experssion of GmELF3 homologs（GmELF3 s）. Meanwhile, the function of GmELF3 Ld was further preliminerily analyzed in transgenic Arabidopsis. The results showed that these five homologs can be grouped into two groups: GmELF3 a/J, GmELF3 b and GmELF3 c are in group A, and GmELF3 Ld and GmELF3 Le are in group B. At the same time, GmELF3 Le contains the most α-helix and has the highest instablility index. These five homologs are all hydrophilic non-trans-membrane proteins. They contained multiple Ser-and Tyr-phosphorylation sites, which allow the precise regulation of their activities. The expression level of B-group genes was much higher than that of A-group genes, and showed obvious differentiation between vegetative and reproductive organs. Such as GmELF3 Ld and GmELF3 Le are highly expressed in leaves, while GmELF3 b and GmELF3 c are highly expressed in flower and seed. The study of transgenic Arabidopsis showed that GmELF3 Ld overexpression can inhibit the expression of FT and CO and delay the flowering time. These results demonstrated that these two types of homologous proteins have the different biological functions and GmELF3 Ld can delay flowering of Arabidopsis Thaliana.