The structure of spleen tyrosine kinase gene in Larimichthys crocea(LcSyk)was analyzed from cloned samples, the expression of LcSyk mRNA in different tissues was analyzed by quantitative real–time PCR (qRT–PCR), and their expression levels were investigated after stimulated with LPS, polyinosinic polycytidynic acid and Vibrio parahaemolyticus. The results showed that the full length cDNA of LcSyk was 2 761 bp, including an ORF of 1 851 bp, encoding with 616 amino acids. The predicted molecular weight and theoretical isoelectric point was 70 527 and 8.13, respectively. The qRT–PCR expression profiles of LcSyk showed that it could express in all 9 examined tissues, including heart, liver, spleen, head–kidney, kidney, gill, intestine, stomach and brain, but the expression levels were different. The dominant expression level was detected in head–kidney, followed by kidney and spleen, but it was the lowest in stomach. Moreover, it was significantly up–regulated after stimulated with Poly I:C, Vibrio parahaemolyticus and LPS. This suggested that LcSyk might play an important role in enhancing immunity against bacteria and virus.