Objective To investigate the incidence, risk factors and the pathogeny of stroke-associated pneumonia(SAP) in acute stroke patients. Methods Clinical data of 642 patients with acute stroke, divided into SAP and non-SAP, were retrospectively analyzed. Univariate analysis and multivariate logistic regression analysis were used to investigate related risk factors for SAP. Pathogens of SAP were analyzed. Results The incidence of SAP in 642 patients with acute stroke was 13.2%,in which early-onset pneumonia(EOP) accounted for 71.8%.Incidences of SAP in the cerebral infarct group, cerebral hemorrhage group and subarachnoid hemorrhage group were 10.9%, 19.4% and 29.4%, respectively(P<0.01). Incidences of SAP in the anterior circulation group, posterior circulation group and anterior-posterior circulation group were 8.3%, 22.3% and 24.6, respectively(P<0.01). The mortality of SAP was 31.7%.The risk factors of SAP were age≥65, diabetes, smoking, dysphagia, hypoproteinemia, antibiotic prophylaxis, dehydrant, H2 -blocker or inhibitors of proton pumps, and nasal feeding. Patients with smoking and nasal feeding had an increased risk for EOP (P<0.01); those with hypoproteinemia and antibiotic prophylaxis had an increased risk for late-onset pneumonia(LOP)(P<0.01). 65 strains of microorgnisms were obtained by sputum culture. Percentages of the Gram-negative bacteria, Gram-positive ones, and fungi were 67.7%, 26.2% and 6.2%, respectively. The major strain was K.pneumoniae in Gram-negative bacteria, Enterococcus in Gram-positive bacteria, and Candida albicans in fungi. Conclusions SAP mostly occurs in the first 72 hours of admission, whose major strains are Gram-negative bacteria. The mortality of SAP is quite high in acute stroke. The incidence of SAP is varied in different types and locations. Risk factors are different between EOP and LOP.