Objective To study the role of the complement receptor 1 and 3 ( CR1 and CR3) on neutrophils in distinguishing bacterial infection in patients with acute exacerbation of chronic obstructive pulmonary disease ( AECOPD) . Methods 40 patients with AECOPD were divided into two groups according to the detection of bacteria in subairway. 20 patients with stable COPD and 20 healthy subjects with no history of smoking were also included. According to Anthonisen criteria, 40 AECOPD patients weredivided into type Ⅰ( 11 cases) , type Ⅱ ( 12 cases) , and type Ⅲ( 17 cases) . The levels of CR1 and CR3 in blood were measured by flow cytometry. Results In AECOPD patients, 25 cases were detected bacteria,and 15 cases were not detected bacteria. The level of CR1 and CR3 were highest in the bacterial infection group than other groups, and highest in type Ⅰ AECOPD patients than other types. ROC analysis showed that CR1 and CR3 had good diagnostic value in bacterial infection in AECOPD, with optimal cutoff values of 11 and 52, respectively. Conclusion CR1 and CR3 may be good index of distinguishing bacterial infection in AECOPD.