Heparin cap imitates the effect of Cloafer's principle on the sealing of intravenous indwelling needles, so as to reduce the medical cost of patients and improve the working efficiency of nurses. Equipped with an arteriovenous indwelling needle, it can be repeatedly and repeatedly punctured for infusion and drug injection, standard locking joint, injection of heparin sodium can prevent blood backflow and anti-coagulation. The application of the heparin cap imitation method can prolong the service life of intravenous in draining needles and reduce the medical costs of patients. It is suggested that, especially for patients with serious liver disease, it is more convenient to use this method and the costs can be reduced.