The invention discloses a grinding method. The grinding method is characterized in that a first abrasive disc is arranged as a model-I abrasive disc, three of second abrasive discs are arranged as model-II abrasive discs, the other three second abrasive disks are arranged as model-III abrasive discs, moreover, the model-II abrasive discs and the model-III abrasive discs are arranged alternately, the spacing between two adjacent inclined blocks is arranged to be equal to the width of a rectangular protrusion, the grinding sequence of the three models is sequentially arranged as the model-I abrasive disc, the model-II abrasive discs and the model-III abrasive discs, a material changing driving air cylinder is located in a hollow connecting shaft, the material changing driving air cylinder isconnected with a central lifting shaft, and an elastic downward pressing assembly sleeves the hollow connecting shaft. According to the grinding method, the abrasive discs of three models can be automatically changed, the grinding efficiency is improved, and automatic production is facilitated.