The invention provides an auxiliary paper cutter applicable to a large plotter printer. The auxiliary paper cutter comprises a longitudinal paper cutting mechanism and a transverse paper cutting mechanism which are arranged on a base, the longitudinal paper cutting mechanism corresponds to the transverse paper cutting mechanism, the longitudinal paper cutting mechanism is a lever type needle holecutting mechanism or a sharp blade type cutting mechanism, the cutting direction of the transverse paper cutting mechanism is perpendicular to the paper discharge direction of the printer, and the paper discharge direction of the longitudinal paper cutting mechanism is the same as that of the printer. By means of the igneous combination of the longitudinal paper cutting mechanism and the transverse paper cutting mechanism, paper discharged from the printer can be rapidly cut into paper with standards sizes convenient to store.