1. A flat data transmission cable, comprising:a plurality of juxtaposed wires;
a plastic layer enclosing on the wires integrally;
a metallic layer formed by a metal material belt arranged on an outer side of the plastic layer in a spiral winding way;
wherein in the length direction of the data transmission cable, the data transmission cable has at least one bending portion, the data transmission cable is formed with a first section and a second section on both sides of the bending portion, and a stable bending angle is formed between the first section and the second section, the wires comprise a plurality of grounding wires and a plurality of signal wires, two signal wires neighboring to each other constitute a signal wire group, the wires are disposed in an equally spaced arrangement, and conductors of the wires have a same outer diameter, and the ratio of the center distance between every two neighboring wires to the outer diameter of the conductor is in the range of 1.4 to 2.8.