The invention belongs to a processing method of a thin-walled inner cone splined hub and in particular relates to a cold extrusion forming method of the thin-walled inner cone splined hub. The method solves the problem that the thin-walled inner cone splined hub is not easy to process by using the prior art. The method comprises the following steps: quenching and tempering a blank, lathing with outside round surface, drilling, boring a tapered bore, performing cold extrusion of a tapered spline, checking and performing phosphorization, wherein molybdenum disulfide is used for lubricating during the cold extrusion process. By adopting the method of the invention, the one-step molding of the thin-walled inner cone spline hole can be realized, the production efficiency is increased by 5-50 times, the product qualification rate is over 95%, and the surface strength of the spline is strengthened through extrusion. The cold extrusion process adopts molybdenum disulfide for lubricating, thusreducing the friction between the extruding cutter and the part, thoroughly solving crack of the thin-walled sleeve during cold extrusion process and successfully using the cold extrusion technology of the cone spline.