A flexible flat cable with a positioning structure that is disposed on the part or on each side of the flexible flat cable close to a signal contact part, and a connector to be used in conjunction with the flexible flat cable has a corresponding positioning structure on a lid body of a movable lid; when the flexible flat cable forms electrical connection with the connector, the movable lid of the connector shall lead the flexible flat cable to be inserted straightly without slant to remove the shortcoming of bad connection between the flexible flat cable and the connector.