The invention relates to a large-bore-diameter high-alloy blank bearizing method, and belongs to the field of extrusion processes. According to the method, in the punching and blank manufacturing process of a material P91 or P92, when the deformation ratio is larger than or equal to 1.35, a cone frustum plus a cylinder are adopted for the head of a punching needle to form a step type needle head, and the diameter of the cylinder is equal to the diameter of a circle on the cone frustum. According to the method, the step type punching needle is adopted to conduct blank manufacturing and chambering production, one-time deformation in the punching process is changed to be continuous twice deformation, the deformation ratio each time is reduced, the pull stress borne by the metal surface is lowered, and surface annular crack generated in the punched blank is prevented.