Abstract： Objective To investigate abnormality of fibrinolysis system in patients with chronic obstructive pulmonary disease (COPD)and the relationship of C-reactive protein (CRP) with it. Methods White blood cell from 121 patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD) was detected. Among them, 30 patients were selected as AECOPD group. When their illness alleviated, they were enrolled in COPD paracmasis group. 20 healthy individuals were enrolled in control group. The plasma levels of CRP, tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) were measured by enzyme linked immunosorbent assay. 90 cases of AECOPD underwent deep venous ultrasonography of both lower limbs. Spiral CT pulmonary angiography was further performed in the patients suspected as pulmonary thromboembolism. Results In 121 patients with AECOPD, peripheral white blood cell count of 32 cases (26.4 %) increased. In 90 patients examined by deep venous ultrasonography of both lower limbs,nine cases (10.0%) accompanied deep vein thrombosis,two cases (2.2 % ) accompanied pulmonary thromboembolism. Compared with control group, the levels of CRP and PAI-1 significantly increased and t-PA significantly decreased in AECOPD group and COPD paracmasis group (all P ＜0.001). The levels of CRP and PAI-1 in AECOPD group were significantly higher than those in COPD paracmasis group ( P ＜ 0.001), while t-PA was significantly lower in AECOPD group than that in COPD paracmasis group ( P ＜0.001). CRP was positively correlated with PAI-1 ( r = 0.871, P ＜0.001) and negatively correlated with t-PA ( r = -0.587, P ＜0.001).Conclusions AECOPD patients have abnormal fibrinolysis and high level of CRP. CRP may be a predictor of fibrinolytic dysfunction.