Objective To investigate the risk factors and prognosis of blood stream infection in patients of intensive care unit (ICU).Methods Clinical data of all patients with culture-positive sepsis were collected from all ICUs of Guangdong General Hospital from October 12th, 2012 to December 1st, 2014 for retrospective study.Physiological characteristics and laboratory data were compared between patients with blood culture-positive sepsis group and patients without sepsis of control group.Logistic regression analysis was made to identify the risk factors for blood stream infection.Patients with blood culture-positive sepsis group were further divided into survivor and non-survivor groups according to the clinical outcomes.Physiological and laboratory data were compared between two groups.Logistic regression analysis was also performed to identify the risk factors for mortality.Results There were 299 patients with positive blood culture sepsis admitted in the ICUs in two years.Of them, 250 patients infected with Gram positive cocci including staphylococcus haemolyticus, staphylococcus epidermidis, staphylococcus capitis and staphylococcus aureus accounting for the majority.There were 174 patients infected with Gram negative bacilli including acinetobacter baumannii, Escherichia coli and Klebsiella pneumoniaesubsp.pneumoniae accounting for the majority.A univariate analysis demonstrated that there were significant differences in hypertension (P =0.001), diabetes (P =0.01), coronary heart diseases and heart failure (P =0.000), chronic renal insufficiency (P =0.000), prolonged mechanical ventilation (P =0.000), pre-admission intravenous administration of antibiotics (P =0.000), and hypoalbuminemia (P =0.008) between culture positive group and control group.A logistic regression analysis demonstrated that diabetes [OR =2.158, 95％ CI (1.230, 3.787), P =0.007], chronic renal insufficiency [OR =13.410, 95％ CI (1.715, 104.879), P =0.013], pre-admission intravenous administration of antibiotics [OR =8.375, 95％ CI (5.267, 13.317), P=0.000] were independent risk factors for bloodstream infections in ICU.In patients with positive blood culture, the non-survivor group had patients with higher advance of old age, higher rate of hypertension, coronary heart diseases or congestive heart failure, tumor and chronic renal insufficiency, prolonged mechanical ventilation and higher incidence of surgery and pre-admission intravenous administration of antibiotics compared with the survivor group.The advance of old age [OR =1.023, 95％ CI (1.008-1.037), P =0.002], prolonged mechanical ventilation [OR =1.055, 95％ CI (1.024, 1.088), P =0.000] and hypoalbuminemia [OR =0.933, 95％ CI (0.898, 0.971), P =0.001] were independently associated with mortality of bloodstream infection in ICU.Conclusions Diabetes, chronic renal insufficiency and pre-admission intravenous administration of antibiotics were associated with the development of blood stream infection in ICU.The advance of old age, prolonged mechanical ventilation and hypoalbuminemia were independent risk factors for mortality in patients with culture-positive sepsis in ICU.