The invention discloses an anti-loose nut. The anti-loose nut comprises a nut body and a supporting block, wherein a notch is formed in the vertical axis of the side face of the nut body, the supporting block is arranged on one side of the top surface of the nut body and is located above the notch, and the top surface of the supporting block is an inclined surface which forms an included angle with the top surface of the notch. According to the anti-loose nut, the defect that a traditional nut only depends on threads is overcome, the nut can be effectively prevented from loosening by changingthe rotation track of the threads, the structure is shockproof and easy to dismount, the maintenance operation of equipment is facilitated, the generation of equipment faults is effectively reduced, and the safe and reliable operation of the equipment is ensured.