A stent delivery system and a second release assembly are disclosed. The second release assembly is configured to control the deployment of a proximal end of a vascular stent and is disposed at a proximal end of the delivery system. The second release assembly includes, sequentially from a proximal end (P) to a distal end (D), a proximal fixing part (1), a restrain part (3) and a control guidewire (5). The restrain part is detachably connected to the proximal fixing part (1) at one end and is coupled to the control guidewire (5) at the other end. With the second release assembly, accurately controlled deployment of the vascular stent is achievable by deploying the proximal end of the vascular stent after the vascular stent has been accurately located.
