A rear-retaining structure for dynamic hip screw (DHS) includes a retaining block and a positioning element. The dynamic hip screw comprises a lag screw, a sideplate, a sleeve with a higher orifice and a lower orifice, and a compression screw. The retaining block of the rear-retaining structure is attached to the sideplate of the dynamic hip screw by the positioning element. A stopper portion of the retaining block is located opposite to the lower orifice of the sleeve. The height of the highest point of the stopper portion in the lower orifice is in inverse proportion to the distance that the lag screw and the compression screw are allowed to slip back in the sleeve from an implant position to the lower orifice namely, the higher the height of the highest point of the stopper portion is in the lower orifice, the smaller the distance for the slip back.
