〔Abstract〕 Objective To identify and characterize the g-type lysozyme in G. zanaensis and analyze its role in host immune system. Methods GzLysG cDNA sequence was cloned by Nest PCR technology. Bioinformatics analysis of the GzLysG protein was carried out by ExPASy, SignalP 5.0, CDD, Cluster Omega and other online software. The GzLysG gene expression pattern in G. zanaensis tissues was detected by RT-qPCR. Results The results showed that open reading frame of GzLysG cDNA was 558 bp in length, encoding 185 amino acids. The molecular weight and theoretical isoelectric point of the reduced protein was 20 478.20 and 9.16, respectively. GzLysG was predicted to be a basic and hydrophilic protein, had no signal peptide and contained the typical catalytic active site, GEWL domain and SLT domain of g-type lysozyme. Advanced structural analysis revealed that GzLysG protein was mainly composed of α-helix and random coil. There was a long and narrow crack on GzLysG molecular surface which was closely related to lysozyme activity. Lysozyme was highly conserved in evolution, with GzLysG showing a close topologic relationship with lysozyme from Danio rerio. Quantitative real-time polymerase chain reaction analysis indicated that GzLysG ubiquitously existed in all examined tissues, with higher mRNA expression levels observed in skin, muscle and gill. Conclusion All those results suggest that GzLysG plays a key role in G. zanaensis immune defensive system.