Objective To study the application value of susceptibility weighted imaging (SWI) in the diagnosis and prognostic evaluation of diffuse axonal injury (DAI). Methods 50 cases of DAI patients who admitted into our hospital between July 2012 and June 2015 were collected. All underwent routine MRI scan and SWI scan. Glasgow coma score (GCS) was performed in all patients after admission. The value of SWI in the diagnosis of DAI was analyzed and its correlation with GCS score was evaluated. Results MR routine sequence of DAI hemorrhagic lesions showed low signal or equal signal on T1WI and low signal on SWI. There was ring-like edema zone around lesions, low signal on T1WI, high signal on T2WI, FLAIR and T2-FFE. The shapes of lesions were uneven. SWI sequences detected a total of 681 DAI lesions, higher than those detected by MR routine sequences. The total volume of lesions detected by SWI was significantly larger than T2- FFE (P<0.05). The number of lesions and the total volume of lesions detected by SWI were negatively correlated with GCS score (r=-0.823, -0.766, P<0.05). Conclusion SWI sequences detected more DAI lesions. The number and volume of DAI lesions were negatively correlated with GCS score and correlated with the prognosis.