The invention relates to the technical field of steering knuckles, and in particular relates to a method for improving the elongation and the shrinkage of a rod part of a steering knuckle. The methodcomprises the steps of heating round steel, upsetting, extruding, pre-forging and finish-forging to obtain a forging blank, and during pre-forging, arranging a transition arc at the joint of the rod part and a disc part of the steering knuckle, and the transition arc forming an annular face around the axis of the rod part. The radius of the transition arc on the side, close to a steering knuckle long lug, of the annular face is R1, R1 is a fixed value, the radius of the transition arc on the side, close to a steering knuckle short lug, of the annular face is R2, the plane where the axis of therod part of the steering knuckle and the axis of a main pin hole are located serves as a datum plane, and R2 is evenly reduced to R1 along with the angle deviating from the datum plane. According tothe method, rod part mold filling can be facilitated, shear damage of an internal metal flow line in the forming process of the rod part of the steering knuckle is reduced, and reduction of the mechanical performance of the rod part is avoided; the rod part can be uniformly distributed, and two sides of the flow line are uniformly and symmetrically distributed; and the stress distribution at the joint of the rod part and the disc part of the steering knuckle is improved.