Individualized anticoagulation management and improvement of the safety and effectiveness of oral anticoagulant have always been the focus of clinicians' attention. D‐dimer, a sensitive marker of thrombosis and coagulation activation, is not only traditionally used in the diagnosis of venous thromboembolism, acute aortic dissection, and disseminated intravascular coagulation but can also be used as a helpful marker in the management of oral anticoagulant, including evaluating the anticoagulation quality, predicting clinical outcomes, and determining the optimal duration and intensity of anticoagulation.