Abstract: An ELISpot diagnosis kit for NMO and its application are characterized in that, the polypeptide fragment specific to NMO effector T-cell is obtained through topological conformation analysis of aquaporin-4 (AQP-4), followed by the structural analyses of the related polypeptides after combination and rearrangement so as to screen out the brand-new polypeptide fragment suitable for NMO disease diagnosis. In the ELISpot experiment, by utilizing the obtained polypeptide fragment, stimulate the effector T-cell in the NMO disease to secrete IL-4, proving the feasibility and scientific value of that polypeptide fragment in the NMO diagnosis. This method is with strong specificity, high sensitivity and easy operations, and it can be developed into the diagnosis kit for the diagnosis and differential diagnosis of NMO in the clinical examination, laying the foundation for the early discovery and treatment of NMO.