Objective:To stady the genetic variations and evolution characteristics of neuraminidase (NA) gene of the novel influenza A(H1N1) virus isolated from Nanjing in 2013. Methods:Viral RNA was extracted from 18 strains of the novel influenza A (H1N1) virus. NA genes were amplified by RT-PCR and then sequenced. The genetic variations and important functional sites of NA genes were analyzed. Results:Compared with recommended vaccine strain in and abroad, the homology of NA amino acid sequences between 18 Nanjing isolates and vaccine strains was above 98.2%. The isolats were grouped into two clusters, with some genetic distance by phylogenetic mapping with the WHO vaccine stain,while closer to the domestic vaccine stain. Compared to the vaccine strains,the variations of amino acids occurred in different sites;1 isolate had a E119K replacement in enzymatically active site;Glycosylation sites appeared to be increased or deleted in the 2013 isolats. Conclusion:High homology was observed in all the NA genes between the strains isolated from Nanjing in 2013 and vaccine strains. The vaccine can continue provide a protection. However,more mutations were accumulated in NA genes in the strains isolated in the late of 2013. Therefore,the monitoring should be strengthened.