The invention relates to a hot-rolled wedge-shaped blank strip steel width control method. The control method comprises the steps that the rough rolling objective and load distribution are completed according to the width of an incoming material of a large head at first; width reduction of all passes of a small head is determined according to the outlet width objective, determined by the large head, of all passes; and reduction is controlled through the large head and the small head of a plate blank, an on-site connection control curve is subjected to long-stroke control, and finally, rectangular control over the plate blank is achieved. According to the control method, the control precision is greatly improved, and the problem that the overall control precision of the width of a plate blank in an existing control method is not high enough is solved.