Diffuse intravascular coagulation(DIC) is a syndrome characterized by activation of coagulation cascades and systemic microthrombus formation. DIC can be presented as abnormal laboratory results of coagulation or severe hemorrhage, thrombosis, and organ dysfunction. DIC is one of the most common syndromes in critically ill patients and is always complicated by sepsis, septic shock, and significantly increased morbidity and mortality. The diagnosis of DIC should be based on medical history, underlying disease, clinical presentation and laboratory results. Given the complicated coagulation network, interaction and feedback regulation between coagulation, anticoagulation, fibrinolysis and inflammation are a tiny part of the whole coagulation network . Different etiology might present similar laboratory results, for example, thrombothytopenia and prolongation of PT. APTT could be found in patients with hepatic failure and DIC patients. Therefore, clincal judgement (history, symptoms and signs) should be valuable in the diagnosis of DIC. In addition to make a diagnosis, labobatory results also help to determine patients' tendency to hemorrhage or thrombosis, and to tell the effectiveness of either replacement transfusion or anticoagulative therapy. Although there are several diagnostic criteria, none satisfactory and highly agreed diagnosis has been achieved clinically. There is no consensus on treatment or treatment duration. Replacement transfusion or anticoagulative therapy should depend on patients' clinical-laboratory phenotype and on risk-benefit ratio.