A medical instrument with three dimensional fixation shape memory intramedullary nail is presented, which is made of shape memory alloy and comprises a rod-shaped body, two distal ends formed at two ends of the rod-shaped body, and a plurality of bent portions on the rod-shaped body and between the two distal ends. Each of the bent portions is a curve on a reference plane, and at least two of the reference planes of the bent portions are cross.
