ObjectiveTo analyze pathogen spectrum of intraabdominal infection in patients in an intensive care unit（ICU）.MethodsIntraabdominal infections and pathogens of 1 330 patients who admitted to ICU from January 2012 to March 2013 were analyzed retrospectively.Results283 patients developed intraabdominal infection, incidence of infection was 21.28%;  133 （47.00%）patients were detected 186 isolates of pathogens, the proportion of gramnegative bacilli, grampositive cocci, and fungi were 68.82%(n=128),28.49%(n= 53), and 2.69%(n=5) respectively. The major gramnegative bacilli were Escherichia coli, Acinetobacter baumannii, and Klebsiella pneumoniae, the major grampositive cocci were Enterococcus faecium,Staphylococcus aureus, and Enterococcus faecalis. The detection rates of pathogens after patients stayed in ICU for ≤2, 3-7, 8-14,and＞14 days were 70.43%（n=131）, 12.90%（n=24）, 10.22%（n=19）, and 6.45%（n=12）respectively; Escherichia coli(n=51) and Enterococcus faecium (n=21)were the main pathogens when patients stayed in  ICU for ≤48 hours, Acinetobacter baumannii was the main pathogen when patients stayed in ICU for ＞48 hours. Most  intraabdominal infection occurred after intestinal tract(53.23%) and hepatobiliary system operation(24.19%). 39 (29.32%) patients isolated at least two kinds of pathogens, 29 of whom isolated 2 kinds of pathogens.ConclusionMost pathogens of intraabdominal infection in ICU patients are detected following  intestinal tract and hepatobiliary  operation, and mixed pathogens are common, predominantly gramnegative bacilli. Escherichia coli and Enterococcus faecium are the main pathogens when patients stayed in ICU for ≤48 hours, opportunistic pathogens are the main pathogens when patients stay in ICU for ＞48 hours.