The invention provides a signal transmission wire provided with a conductive plastic material layer. The invention relates to the technical field of a signal transmission wire and in particular relates to an EMI (Electro-Magnetic Interference) protection aspect of the signal transmission wire. The technical defects that the conventional signal transmission wire has electro-magnetic interference, and an EMI protection screening layer of a metal weaving layer has disadvantages of high cost, easiness of corrosion, difficult control in screening effects and the like can be solved. The signal transmission wire at least comprises a metal lead wire provided with an insulating layer; a conductive plastic material layer is arranged outside the metal lead wire provided with the insulating layer; and an insulating coating is further arranged outside the conductive plastic material layer. According to the signal transmission wire provided by the invention, the conductive plastic material layer is used as the EMI protection screening layer; a conductive plastic material is further named as a conductive macromolecule plastic and has better conductivity, anti-static property and the like, so that the EMI protection problem of the signal transmission wire can be effectively solved; the production cost is low and the signal transmission wire is easy to machine; and the surface resistivity can be controlled by a content of added conductive fillers.