Profuse blood loss affects blood coagulation to various degrees. However, whether bleeding speed affects coagulation remains uncertain. This study aimed to evaluate the effect of bleeding speed on coagulation function. A total of 141 patients in the Department of Thoracic Surgery of our hospital were evaluated between January 2007 and February 2014. There are two groups of patients, those who received decortication for chronic encapsulated empyema were called the slow-bleeding group, and those who received thoracoscopic upper lobectomy were called the fast bleeding group; each group was further subdivided into three: group A, 1000 ml ≤ bleeding amount < 1500 ml; group B, 1500 ml ≤ bleeding amount < 1700 ml; group C, 1700 ml ≤ bleeding amount < 2000 ml. Then, coagulation function was assessed in all patients before and during surgery and at 1, 2, and 24 h after surgery, measuring prothrombin time, activated partial thromboplastin time (APTT), fibrinogen, blood pressure, hematocrit, hemoglobin, and platelets. Bleeding duration was overtly longer in the slow-bleeding group than that in quick bleeding individuals (2.3 ± 0.25 h vs. 0.41 ± 0.13 h, P < 0.001). Fibrinogen, hematocrit, hemoglobin, and platelets strikingly decreased, whereas prothrombin time and APTT values significantly increased with bleeding amounts in both quick and slow-bleeding groups. Interestingly, compared with slow-bleeding patients, coagulation indices at each time point and bleeding amounts had significant differences in the quick bleeding group.Increased consumption of coagulation factors in quick bleeding may have greater impact on coagulation function.