Singapore grouper iridovirus (SGIV) was an important piscine infectious virus. The virus caused more than 90% mortality in grouper and resulted in heavy economic losses in grouper aquaculture. SGIV ICP46 was an immediate-early (IE) gene, may be associated with cell growth control and could contribute to virus replication. A leucine-rich nuclear export signal (NES) in SGIV ICP46 was predicted. To identify the function of the NES in protein translocation, three recombinant plasmids including pEGFP- ΔNESa (containing the fragment before NES) , pEGFP- ΔNESb (containing the fargment after NES) and pEGFP- ΔNESc (containing the complete ICP46 fragment without NES) were constructed and used to track the movement of the protein lacking the NES in GP (Grouper embryo) cells. As the results showed, in pEGFP-ICP46-transfected cells, the fluorescence signal was observed mainly in the cytoplasm, outside of the nucleus. However, in pEGFP-ICP46-ΔNES-transfected cells, the fluorescence signal was scattered throughout the whole cell. These results indicated that the NES is essential for the translocation of SGIV ICP46 from the nucleus to the cytoplasm.