The present invention relates to a method for forming the spacer of slitting machine. Firstly, the material is provided, then various processing methods are applied to form the spacer with smooth surface and a plurality of fixed-distance columns. Compared to the conventional spacer, the weight of lightweight spacer of the invention is reduced by 50%±10%. Additionally, the lightweight spacer of the invention not only is placed on the other positions of slitting machine, but also is suitable for the machines of other relevant fields.