The application discloses a flat cable assembly, which includes a plurality of cables arranged in a row and an insulating film. The cables have a center line and include connecting portions, a signal wire and a grounding wire respectively. The connection portions are located on one side of the center line. The insulating film is disposed on the connecting portion of any one of the cables and located on one side of the central line. The cables are exposed from the insulating film. The insulating film is disposed on a single side of the cables, whereby the cables are exposed from the insulating film. The flat cable assembly is easily manufactured and the amount of the cables therein can be varied according to real practice condition. The grounding wire is integrated to each cable, whereby the flat cable assembly has an excellent anti-EMI effect and performance in signal transmission.