The invention discloses a pressurized intramedullary expanding 
interlocking screw. The pressurized intramedullary expanding 
interlocking screw comprises a main intramedullary screw, an inward-expanding screw, a pressurized 
set screw and an arc 
tail end screw plate. A hollow hole is formed in a main rod of the main intramedullary screw, the near end of the main intramedullary screw is provided with an axial inner hole connected with the pressurized 
set screw through threads, the far end of the main intramedullary screw is provided with a set of 
petal type wing-shaped sheets which can be driven by the inner supporting force to open outwards, and at least two tip blades are arranged on the outer side of each wing-shaped sheet; the inward-expanding screw is screwed down to stretch the wing-shaped sheets at the far end of the main intramedullary screw. The pressurized 
set screw can be screwed into the axial inner hole in the near end of the main intramedullary screw, and a 
screw cap is arranged at the 
tail of the pressurized set screw, and the whole length of the pressurized intramedullary expanding 
interlocking screw can be shortened and prolonged by screwing in and out the pressured set screw. The arc 
tail end screw plate is provided with an opening hole where the pressurized set screw can penetrate, and is abutted to an acted body through the 
screw cap at the tail of the screwed pressured sleeve screw. According to the pressurized intramedullary expanding interlocking screw, the mini-invasive 
surgical treatment can be achieved for an olecranal fracture and a fibula external 
ankle fracture, and the functions of 
elbow joints and 
ankle joints can be recovered early.