The present invention discloses a flat cable, which comprises signal unit sets and the insulating layer which wraps and fixes the signal unit set. The signal unit set is formed by at least two signals units arranged substantially on the same plane at an interval or side by side. The left and right sides of the signal unit set are directly wrapped by insulating layers. The insulating layer is formed by splicing and bonding at least one insulating film, and the splicing points at two ends of the insulating film are located on the upper side or the lower side of the signal unit set. In the flat cable of the present invention, the length of the overlapping portion can be set as required, effectively preventing the phenomenon such as insulating film tear and short circuit caused by insulating film tear.