Objective To study the diagnostic value of magnetic susceptibility weighted imaging (SWI) in acute cerebral infarction complicated by cerebral microhemorrhage. Methods 70 patients who had acute cerebral infarction and were admitted into the hospital during January 2013 to February 2015 were selected as the research objects. All of them received routine MRI, DWI and SWI sequence scanning. The positive detection rates of different sequence scanning for cerebral microhemorrhage were compared and analyzed. Results There were 38 cases (54.29%) of positive CMB detected by SWI, which mainly distributed in the basal ganglia-thalamus areas, the cortex-subcortical areas and relatively less in brain stem. There were round and punctiform low signal lesions on SWI sequence. MRI routine sequence showed that CMB was negative. There were 6 cases (8.57%) of positive CMB showed by DWI. The positive detection rate of SWI for CMB was significantly higher than that of routine MRI and DWI sequence, and the differences were statistically significant (P<0.0001). Conclusion The positive detection rate of SWI sequence for acute cerebral infarction complicated by cerebral microhemorrhage was significantly higher than of routine MRI and DIW, which can be used as the first choice for the diagnosis of cerebral microhemorrhage.