Objective To investigate the clinical significance of the level of plasma D-dimer and plasma fibrinogen in patients with COPD.Methods According to severity stage,the plasma D-dimer and plasma fibrinogen level were measured in 122 patients with COPD.30 healthy subjects were included as controls.All the measures of D-dimer and plasma fibrinogen were compared between the groups.Results The levels of D-dimer and fibrinogen in 122 patients were significantly higher than those in the control group(P0.05),and the levels of D-dimer and fibrinogen in the acute exacerbation were significantly higher than those in the stable.In 75 patients with acute exacerbation of COPD patients,the levels of plasma D-dimer and fibrinogen in mild,moderate,severe and critical patients were compared,and the group differences were statistically significant(P0.05).Conclusion The patients with COPD are in a state of hypercoagulability,and the levels of plasma D-dimer and fibrinogen are related to the severity of COPD attack.To monitor and preventively use anticoagulant,the use of thrombolytic agent is necessary.