A perforation device for making roll of plastic bag with an opening and a perforation line on each bag, comprising a cutting unit, an anvil unit and a expanding board, wherein, the cutting unit involves a main unit whereto are fitted with a toothed blade and a specified number of compressing blocks, the expanding board serving to expanding the material bag, the toothed blade on the cutting unit serving to cut and punch a surface of the material bag, making a roll of plastic bags each having an opening on one side, thereby fully automated packaging can be achieved by installing the present invention on an automatic weighing and packaging machine or a in conveyor packaging line for convenient packaging process, to reduce labor cost and enhance packaging efficiency.
