In this study, pcDNA3.1 (+) -Bs5-10 (GenBank login number is MH234474) was constructed in series of B cell linear epitopes of II type GCRV VP5 and NS38, and was packaged into nanoscale chitosan particles. Grass carp (11-12 cm, 25-30 g) without GCRV were randomly divided into blank control group, blank control group-GCRV attack group, bare empty carrier injection group, Chitosan oligosaccharide coated empty carrier oral group, naked DNA vaccine group (at day 1 and 29, each tail fish was injected 10 μg pcDNA3.1 (+) -Bs5-10), and Chitosan oligosaccharide coated DNA vaccine oral group(each tail fish took orally 50 μg pcDNA3.1 (+)- Bs5-10 everyday, which had been carried between 1-3 days, 15-17 days and 43-45 days). Then the protective ability and specific antibody level of vaccine need to be evaluated at the temperature of 28 ℃. The results showed that the relative percent survival of the naked DNA vaccine group and the Chitosan oligosaccharide coated DNA vaccine oral group were 66.67 % and 50 % respectively, and the level of serum anti VP5 and anti NS38 IgM in these two groups increased significantly with the enhanced immunization (P<0.05). Furthermore, the specific IgM level in the former group was significantly higher than the latter (P<0.05) at the corresponding time point (22 days