The anti-loose principle of the spring washer is that after the spring washer is flattened, the spring washer generates a continuous elastic force, so that the nut and the threaded connection of the bolt maintain a frictional force and generate a resisting torque, thereby preventing the nut from loosening. At the same time, the sharp corners at the opening of the spring washer are respectively embedded in the bolt and the surface of the connected member, thereby preventing the bolt from rotating relative to the connected member.