This paper presents a novel anti-loosening nut design, called “SL nut”. It features an anti-loosening ring with an interference fit with the bolt thread, thereby squeezing the bolt in the radial direction. Using the finite element analysis, the prevailing and loosening resistance torques of the SL nut were investigated during tightening and untightening processes. The nut demonstrated the largest prevailing and loosening resistance torque among the nuts with prevailing torque. Importantly, both torques remained steadily large during tightening and untightening process. The magnitude of the torques can be controlled by adjusting the overlap length of anti-loosening ring. This new type could become a cost-effective solution for a variety of industrial applications. Additionally, the approach we employed could spur further development of anti-loosening nuts.