Abstract: Toll-like receptors (TLRs) play an indispensable role in the immune response of fish for pathogen recognition and triggering immune reaction, and interleukin-1 receptor-associated kinase 4 (IRAK4) is one of the important components of TLR signaling pathway. We cloned the sequence of lmirak4 from Lateolabrax maculatus and analyzed its expression pattern and intracellular localization. The total cDNA sequence of lmirak4 ORF was 942 bp, encoding 313 amino acids with an N-terminal death domain and a central protein kinase domain. The Blast analysis shows that the deduced amino acid sequence of Lmirak4 shared high identity with other fishes. The tissue distribution analysis indicates that lmirak4 expressed in all the examined tissues with various expression levels and the highest expression was detected in head-kidney. Besides, the expression level of lmirak4 increased significantly in head-kidney, spleen and liver after infection of Vibrio harveyi and Streptococcus agalactiae. The eukaryotic expression plasmid of Lmirak4 was primarily expressed in the cytoplasm and membrane of HEK293T cells. In contrast, Lmirak4 showed a uniform presence of existence in L.maculatus primary kidney cells.