The aim of this study was to analyse the application value of CT and MRI combined examination for the diagnosis of acute cerebral infarction. It was an observational study carried out from March 2017 to April 2018. All the patients of acute cerebral infarction, diagnosed on the basis of clinical and laboratory findings and underwent brain CT and MRI examination within 6 hours after the onset of the disease, were included in the study. A total of 70 patients were diagnosed, which included 40 (57.14%) males and 30 (42.86%) females. Median age was 64 years. The confirmed diagnosis rate of acute cerebral infarction by CT combined with MRI was higher than that by CT examination alone (p<0.001). The positive rates of the brainstem were statistically different between the two methods (p=0.007). The diameter of infarct lesion in CT combined with MRI was longer than that in CT examination alone (p<0.001). CT combined with MRI can be used as the first choice for early diagnosis of acute cerebral infarction, particularly of brain stem.