Antithrombin III is one of the most important antibacterial substances in the human body, and the normal level is 230-350g/L. Antithrombin III must be combined with heparin to function, and the anticoagulant effect can be expanded to more than 1000 times. Antithrombin III can inactivate a variety of coagulation factors such as Factor X, Factor V, Factor II and Factor I in the human body, thus exerting an effective anticoagulant effect to ensure that the human blood does not form clots and at the same time does not form bleeding situations. If antithrombin III activity decreases, the body can develop various thrombotic disorders, including pre-thrombotic states. Decreased antithrombin III activity is seen in patients with severe liver disease, production of antithrombin III antibodies, etc. If antithrombin III activity is increased, the body’s anticoagulant activity is enhanced, and various bleeding disorders are also likely to occur. Therefore, antithrombin III must be maintained within the normal concentration range in order to maintain the normal physiological functions of the body.