The invention relates to a pre-treatment method for electroplating plastic. The surface of a workpiece is wiped through isopropyl alcohol, and the workpiece wiped through the isopropyl alcohol is put into a cavity of a plasma generator and then is subjected to plasma treatment; then, the workpiece subjected to the plasma treatment is taken out and then is washed with water. The pre-treatment method has remarkable plastic cleaning, activating and roughening effects and is carried out at a room temperature; materials are not deformed so that influences on performances of materials are avoided. Meanwhile, the pre-treatment method is high in safety and adopted main equipment adopts a human-computer interface and visualized operation; a treatment flow can be controlled at any time, the treatment time is short and the treatment efficiency is high; the pre-treatment method is applicable to plastic electroplating of almost materials including ABS (Acrylonitrile Butadiene Styrene), PA (Polyamide), PP (Polypropylene) and the like, electroplating bath liquid is not needed and expensive environment-friendly equipment is also not needed, so that the cost can be remarkably reduced and the environment pollution is avoided.