Objective To explore the computer tomography (CT) and magnetic resonance imaging (MRI) of lacunar infarction (LAC) the diagnosis results, and analyze the diagnostic value of CT. Methods From January 2012 to July 2014 treated in our hospital department of internal medicine nerve with 178 cases of LAC patients. With MRI was as the observation group, CT checked the corresponding note was for the control group. The location, the size of the examination of two groups were compared, and 1 months after the re examination of patients were examined by MRI and recorded lesions. Results MRI was detected in 1770 lesions, 420 lesions were found in CT group. Total was CT MRI detectable detectable in total 4.2 times. And group MRI for lesions than 5mm detection rate was significantly higher than that of group CT and 6-15mm detection rate was relatively lower. At the end of the re examination of patients according to the first check size packet found lesions showed obvious reduction, the most significant one was the aged patients with 11mm. The differences were statistically significant (P<0.05). Conclusion LAC patients in the first lesions appear frequently, more than 5mm. The total number of lesions detected by MRI is higher than that of CT and MRI on the detection of the total, less than 5mm lesions have obvious advantages. But in the early stage of the disease appeared in water, which need accurate diagnosis, timely to ensure the late treatment, MRI has more clinical value.