A medical guide wire comprises a metal core (1), a coil (2), a delivery element (3) and a boss (4). The metal core (1) has a variable-diameter structure, which consists of a linear structure (1-3), a stepped structure (1-2) and a linear structure (1-1) from a proximal end to a distal end. The number of the coil (2) is one or more, and the coil(s) is/are fixed on the linear structure (1-1) and the stepped structure (1-2) at the distal end of the metal core (1). The number of the delivery element (3) is one or more, and the delivery element(s) is/are fixed to the stepped structure (1-2) of the metal core (1). The boss (4) is fixed on the stepped structure (1-2) of the metal core (1) behind the delivery element (3). When the medical guide wire is delivering an implant instrument, the delivery element on the medical guide wire makes each segment of the implant instrument receive even resistance by rubbing the inner wall of the implant instrument, thereby integrally delivering the implant instrument into the human lumen.
