Cyprinid herpesvirus 3 (CyHV-3), also known as koi herpesvirus (KHV), is the causative agent of an emerging and mortal disease in common (Cyprinus carpio carpio) and koi (Cyprinus carpio koi) carp. Since its emergence in the late 1990s, KHV has caused severe financial and economic losses in both koi and common carp culture industries worldwide. CyHV-3 contains an interleukin-10 like open reading frame (ORF134), which has been identified from multiple members of Herpesvirales and Poxviridae. Here in this study, ORF134 of CyHV-3 was amplified by RT-PCR. It is 624 bp in full-length with an intron and encodes a peptide of 179 amino acids. Multiple sequence alignment indicated that ORF134 shared 23.5% amino acid sequence similarity with carp IL-10. Homology modeling suggested that ORF134 had a similar three-dimensional structure with vIL-10 encoded by EBV, but shared low sequence similarity with other vIL-10. To analysis the expression profile of ORF134, the coding region of ORF134 was cloned into pcDNA3.1 vector and expressed in 293T cells. The results suggested that ORF134 could secrete from expressed cells, but different from other identified viral IL-10 homologs, ORF134 could not form homodimer under non-reduced condition. Further study showed that soluble fusing protein of ORF134 was also expressed in E. coli. 