Abstract: Because of the characteristics of Fe-based shape memory alloy, the self-locking frictional moment in the thread connection of a new nut made of the alloy is considerably increased, and the uniformity of the axial load distributed among every screw tooth is also improved. As a result, the failure phenomena, such as thread-connection loosing, disengaging and thread fatigue fracture, are effectively prevented. In this paper the anti-breaking mechanism of the nut is analyzed. A calculation model of the load distribution in the newly-designed bolt connection is established, and the anti-breaking performance of the nut is appraised based on comparison with ordinary bolt connections.