An electrostatic discharge guide using metal sputtering process and modifying plastic case is applied to an electronic device. The plastic case and a metal case are laminated. The plastic case is defined with a tip portion spaced from the metal case on side wall thereof. A conductive layer formed on the surface of the plastic case opposite to the metal case extends to the tip of the tip portion, and is electrically connected to a ground of the electronic device. Therefore, when electrostatic charges accumulated on the metal case exceed a specific value, the static electricity is discharged to the ground of the electronic device based on the point discharge principle, instead of causing an electric shock to a user.