The invention discloses a method and device for size cooperative control of silicon steel. The method comprises the following steps of obtaining the width of a strip steel of an order in a hot rollingplan; controlling the tolerance of the trimming width according to the width of the strip steel of the order; obtaining a width curve of the hot rolling strip steel; controlling the minimum width ofthe strip steel according to the width curve of the hot rolling strip steel; obtaining the end-user requirements of the order in the hot rolling plan and the thickness of the finished silicon steel; controlling the order requirements of the silicon steel according to the end-user requirements and the thickness of the finished silicon steel; obtaining detection data of a hot rolling camber meter; and controlling an outline of the silicon steel according to the detection data. By means of the method and device for the size cooperative control of the silicon steel, the width cooperative control and the outline cooperative control are achieved, and the size cooperative control of the silicon steel is achieved, so that in the prior art, the problems of cutting edge narrow rule and cold rollingtransverse thickness difference without feedforward control are solved in the production process of the silicon steel, and the technical effect of improving the production stability and the level of the finished product size of the silicon steel is achieved.