Nut and tool spanner for dismounting and mounting same

The utility model is applicable to the field of locking piece structures, and provides a nut and a tool spanner for dismounting and mounting the nut. The nut comprises a body part on which a threaded hole is formed; the outer lateral surface of the body part takes a conical surface shape or cambered surface shape; and a stressed groove is formed on the body part. The tool spanner comprises a sleeve part which can be sleeved on the body part; and a raised block which can be clamped in the stressed groove is arranged at the inner side of the sleeve part. According to the nut and the tool spanner for dismounting and mounting the nut, which are provided by the utility model, the outer lateral surface of the nut is set to be a conical surface or a cambered surface and the nut cannot be dismounted by using a conventional tool and can be only dismounted by using the special tool spanner, so that the nut has high safety and excellent burglarproof performance and is convenient to operate.