A towing anchor capable of extending wing plate and an installation method therefor are provided. The towing anchor includes a main anchor plate and two wing plates which can slide outwards relative to the main anchor plate and will not be detached from the main anchor plate. The main anchor plate is anchored with a mooring steel cable connected to a towing vessel. The main anchor plate is further provided with a limit cable-receiving groove, in which first, second and third fixed pulleys are respectively provided correspondingly to each of the two wing plates. One end of a tensioning steel cable is fixed to an inner edge of the wing plate, and the other end of the tensioning steel cable sequentially surrounds the third, second, and first fixed pulleys and then passes through an opening formed at middle position of the groove to be connected to the towing vessel.