Objective To explore the value of the apparent diffusion coefficient (ADC) ratio and fractional anisotropy (FA) ratio of magnetic resonance (MR) diffusion tensor imaging (DTI) in evaluating the clinical symptoms, prognosis of cervical spondylotic myelopathy (CSM). Methods Thirty-six healthy subjects and fifty CSM patients were involved and received MRI examination. Regions of interest (ROIs) were selected in the ventral funiculus (VF), lateral funiculi (LF), dorsal funiculus (DF), and central gray matter (GM) for ADC and FA measurements. In the control group, ADC and FA ratios were calculated using the original values at the C_3/4, C_4/5, C_5/6, and C_6/7 levels to divide the corresponding values at their C_1/2 levels. In the CSM group, ADC and FA ratios were calculated using the ADC and FA values at the most compressed levels to divide the corresponding values at their C_1/2 levels. In the control group, the variances of the two ratios were compared between different cervical levels and ages. CSM patients were divided into mild, moderate, and severe group according to the preoperative Japanese Orthopaedic Association (JOA) scoring system, and were divided into well, moderate, and poor group according to the postoperative JOA recovery rates. Correlations between DTI parameters, DTI ratios of the VF, LF, DF, and GM of the CSM patients and the JOA scores, JOA recovery rates were assessed among different clinical symptom subgroups and prognosis subgroups. Results In control group, DTI ratios (ADC ratios and FA ratios) in VF, LF, DF, and GM were significantly different between C_3/4, C_4/5, C_5/6, and C_6/7 levels(P<0.05), but not found between different age subgroups. Correlations between DTI ratios of the VF, LF, DF, and GM and JOA scores, JOA recovery rates were significantly superior than the correlations between DTI parameters and JOA scores, JOA recovery rates (P<0.05 or P<0.01), with the FA ratio being superior to the ADC ratio. Compared with normal control group, the ADC ratios increased gradually in order and FA ratios decreased gradually in the mild, moderate, and severe injury subgroups (P<0.05). Compared with normal control group, the ADC ratios increased gradually in order and FA ratios decreased gradually in the well, moderate, and poor recovery subgroups(P<0.05). Conclusion DTI ratios might eliminate the influence of age in evaluating the clinical symptoms and prognosis of CSM. Therefore DTI ratios, compared with DTI parameters, may better evaluate the clinical symptoms, prognosis of CSM.