The invention relates to a nut machining method which includes the following steps that a nut is provided, an inner surface extending in one direction is arranged on the nut, a smooth portion and a thread portion are arranged on the inner surface, the smooth portion is ground through a grinding machine, and a super polishing part rotates in the direction and stretches into the nut to grind the thread portion. The nut machining method can be used for grinding the nut with the high helical angle.