An exemplary grinding method includes, firstly, providing a holding device including a first rotatable pressing portion and a second rotatable pressing portion, and providing a base. Then a number of workpieces are placed into a groove of the base. Two blocking members identical in shape are placed in the groove, with the workpieces therebetween. The blocking members are moved towards the workpieces to closely align with the workpieces. The sizes of the blocking members are compared with that of each workpiece, and then the blocking members are removed. If the workpieces are larger than the blocking members, the workpieces are thereafter held between the first and second pressing portions. Next, the base is removed and the first and second pressing portions are driven to rotate. Subsequently, the workpieces are ground, and then a number of finished products are obtained.