Objective To investigate the value of conventional magnetic resonance imaging（MRI）and diffusion tensor imaging（DTI）in the quantitative diagnosis of neuromyelitis optica（NMO）with normal spinal cord as control. Methods 20 NMO patients（NMO group）and 20 healthy people（control group）from September 2020 to March 2022 were selected，and they all underwent routine MRI and DTI examinations. The routine MRI performance，average diffusion coefficient（ADC），partial anisotropy（FA），and average diffusion rate（MD） were calculated in both groups；the receiver operating characteristic（ROC）and area under ROC（Area under ROC）were used to analyze the diagnostic value of conventional MRI and DTI quantitative parameters. The parame⁃ ters of the highest diagnostic sensitivity and specificity were screened out and they were combined with serological NMO⁃IgG to analyze their diagnostic value for NMO. Results The ADC and MD were higher in the NMO group than in the control group，while the FA value was lower（P < 0.05）；Conventional MRI had the highest specificity of 100.00% for the diagnosis of NMO，ADC had the highest sensitivity of 90.00% for the diagnosis of NMO，and the AUC of 0.811 was the highest. The combined diagnosis of both methods further increased the AUC of 0.918； the AUC of positive serum NMO ⁃ IgG plus conventional MRI and ADC was 0.955，with the sensitivity of 90.00% and the specificity of 95.00%. Conclusion Conventional MRI and DTI quantitative parameters can be used in the early diagnosis of NMO. The clinical combination of serum NMO⁃IgG can be applied for early auxiliary diagnosis to improve the diagnostic efficiency and it provides a reliable basis for the development of individualized therapies.