The invention discloses a wheel disc forging and a manufacturing method thereof and belongs to the technical field of mechanical manufacture. The manufacturing method further optimizes material components, controls the upper limits of C and Mn content, improves Ni content, reduces content of harmful P and S, reduces Si content and temper brittleness of Mn, utilizes an electroslag remelting process so that the purity of molten steel is improved, and utilizes post-forging heat treatment comprising two normalizing processes so that materials are further homogenized and grains are fined. Raw materials adopted by the manufacturing method comprise C, Mn, Si, P, S, Cr, Ni, Al, Cu and Fe. The manufacturing method comprises the following steps of electrode blank smelting, electroslag remelting smelting, steel ingot annealing, steel ingot forging, post-forging heat treatment, property heat treatment, and property and microstructure examination. The wheel disc forging obtained by the manufacturing method and the manufacturing method have the advantages that a ratio of chemical components is reasonable; material purity is high; forging effects on the core are good; density of the metal microstructure is good; and the problems that a wheel disc forging obtained by the existing manufacturing method is unqualified in the forging flaw detection and a mechanical property especially such as a material ductile-brittle transition temperature does not satisfy the requirement are solved.