Objective To investigate the relationship between hemorrhagic transformation (HT) after acute iachemic infarction and cerebral microbleeds (CMB) or other related risk factors, and analyze the possible preventive methods of HT. Methods Three hundred and forty-eighty in-patients with acute infarction, consecutively admitted to our hospitals from June 2009 to December 2010, were included and related risk factors were registered. All patients were performed GRE-T2*WI to detect the presence of CMB and hemorrhage transformation. Logistic regression analysis was used to assess the relationship between HT and related risk factors by Forward Stepwise. Results HT occurred in 35 (10.06％) of the 348 patients with acute infarction. Nineteen patients (8.92％) experienced HT in 213 patients with atherosclerotic infarction. Eleven patients (39.29％) experienced HT in 28 patients with cardioembolic infarction and 5 (26.32％) experienced HT in 19 patients with undetermined etiology infarction. No patient experienced HT in patients with lacunar infarction. The results of multivariate binary logistic regression showed that risk factors of CMB were cardioembolic infarction (OR=5.338,95％CI: 1.926-14.796, P=0.001), undetermined etiology infarction (OR=6.843, 95％CI 1.848-25.346,P=0.004), and scores ofNIHSS (OR=1.181, 95％ CI: 1.085-1.284, P=0.000), and that protective factor was low density lipoprotein (OR=0.637, 95％CI: 0.414-0.979, P=0.040). Conclusion The rates of HT vary in different subtypes of acute ischemic infarction and the rate of HT among cardioembolic infarction is the highest. The risk factors of HT are cardioembolic infarction, undetermined etiology infarction, and scores of NIHSS, and the protective factor is low-density lipoprotein. CMB is not related with HT.