A device for puncturing a heparin cap and a vascular access system. The device for puncturing the heparin cap comprises a connecting device (515 , 621 , 720, 820, 920) adapted for being fluid communicably coupled with a medicine liquid supply device , a guide device (511 , 611 , 710 , 810 , 910) suitable for accommodating at least a part of the heparin cap ,and a puncturing device (520 , 631 , 730 ,830, 930) used for puncturing the heparin cap and configured to be in fluid communication with the connecting device and at least partially located in a predetermined location in the guide device. The predetermined location is configured to make the puncturing device insert the sealing rubber of the heparin cap in the appropriate location and in the appropriate relative angle to the heparin cap and eventually penetrate the sealing rubber in the process of at least a part of the heparin cap being put into the guide device. The device can allow medical staff to complete the puncture to the heparin cap safely, easily , quickly and effectively , greatly reduce or eliminate the waste of medicine liquid in the subsequent transfusion process, and help medical staff more thoroughly rinse the residual medicine liquid inside the heparin cap.
