Ordinary flat washers only serve to distribute pressure and protect the surface of the workpiece, and do not have the ability to prevent loosening. Anti-loosening washers rely on tooth surface interlocking, conical surface interlocking or elastic compensation structures to continuously maintain the pre-tightening force of bolts under vibration and alternating loads, effectively preventing thread loosening. They are widely used in scenarios with high requirements for connection reliability, such as high-speed rail, photovoltaic, and precision machinery.