Prothrombin time is the time required to cause plasma coagulation after the conversion of prothrombin into thrombin after the addition of excess tissue thromboplastin and appropriate amount of calcium ions to plasma lacking platelets. High prothrombin time, that is, prolonged time, may be due to a variety of reasons such as congenital coagulation factor abnormalities, acquired coagulation factor abnormalities, abnormal blood anticoagulation status, etc. The main analysis is as follows: 1. Congenital coagulation factor abnormalities: abnormalities in the generation of any of coagulation factors Ⅰ, Ⅱ, V, Ⅶ, X in the body will lead to prolonged prothrombin time. Patients can supplement coagulation factors under the guidance of doctors to improve this situation; 2. Acquired coagulation factor abnormalities: common ones include severe liver disease, vitamin K deficiency, hyperfibrinolysis, diffuse intravascular coagulation, etc. All these factors can lead to coagulation factor deficiency in patients and cause prolonged prothrombin time. Need to clarify the specific cause for targeted treatment, for example, patients with vitamin K deficiency can be treated with intravenous supplementation of vitamin K1 to promote the prothrombin time back to normal; 3, abnormal blood anticoagulation status: the presence of anticoagulant substances in the blood or the patient’s use of anticoagulant drugs, such as aspirin and other drugs with anticoagulant effect, will affect the coagulation mechanism, which in turn prolongs the prothrombin time. Patients are advised to discontinue anticoagulant medications and change to other modalities of treatment under the guidance of a physician. Prothrombin time prolongation of more than 3 seconds is clinically significant. If it is only high not exceeding the normal value of 3 seconds it can be closely observed and generally no special treatment is needed. If the prothrombin time is prolonged for too long, the specific cause needs to be further investigated for targeted treatment.