The application discloses a flat cable assembly, which includes a plurality of cables and an insulating film. The cables are arranged in a row and have a center line. The plurality of cables respectively have a first connecting portion and a second connecting portion symmetrically disposed with the first connecting portion, a signal wire and a grounding wire. The first connection portion is located on one side of the center line, and the second connection portion is located on the other side of the center line. The insulating film is provided on the first connection portion and the second connection portion of any one of the plurality cables. The two sides of the insulating film do not protrude outward from the two outermost cables, and the two surfaces of the insulating film in the direction perpendicular to the center line are planes.