The invention relates to the technical field of medical devices, in particular to a stent delivery system. The stent delivery system comprises a pushing guide wire, an import sheath and a backwashingplug, wherein the pushing guide wire is used for delivery of a stent, and is segmentally arranged; the import sheath is used for in-vitro mounting of the stent and the pushing guide wire, and the import sheath is in butted connection with a microcatheter; the backwashing plug is used for being connected with a syringe and the import sheath. As the backwashing plug is arranged to be connected withthe syringe and the import sheath, compared with a traditional way that backwashing is conducted with a Y valve, the stent can be conveniently and quickly washed by using the syringe, the backwashingoperation is simple, and less time is consumed. By segmentally arranging the pushing guide wire, all segments of the pushing guide wire can be made from materials with different strengths and toughnesses and/or different thicknesses, personalized demands of a patient can be met, and according to the position of a lesion, the suitable materials and lengths of the delivery segment and the pushing segment of the stent are selected.