Vaccination is the most promising strategy to combat infectious diseases. Vaccine adjuvants are considered as key components in modern vaccinology since they provide the necessary help in enhancing the immune responses. This study evaluated the protective effects of poly (I:C), chitosan oligosaccharides (COS) and chitosan as new adjuvants in enhancing immune response and inhibiting GCRV replication using inactivated GCRV vaccines. Complete Freund's adjuvant (CFA) was used as a control adjuvant, and the survival rate of each group of grass carp was assessed. The CiIgM protein levels in sera were obviously boosted and sustained by the three novel adjuvant supplies, examining by enzyme-linked immunosorbent assay (ELISA) and western blotting (WB) methods. Meanwhile, mRNA expression of CiIgM in spleen and head kidney were elevated, checking by real time quantitative RT-PCR (qRT-PCR) assays. The Th1, not Th2 type immune responses, pro-inflammation cytokines and innate antiviral genes were also reinforced in spleen and head kidney tissues at early stages. The GCRV replication was significantly reduced post GCRV injection. The tissue sectioning showed a significant reduction in tissue damage in muscles, intestines, and hepatopancreatic tissues under the protection of the three adjuvants. The results indicated that poly(I:C), COS and chitosan can serve as novel and efficient adjuvants in inactivated vaccine in grass carp.