The invention discloses a tyre dismounting machine, comprising a rack, a jacking device, a conveyer device used for conveying the jacking device in and out the bottom of the rack, a brake block device arranged on the conveyer device and a rimmer pressing device arranged at the top of the rack. The rimmer of the invention is positioned by the jacking device and is conveyed to the bottom of the rimmer pressing device by the conveyer device, rubber tyre is placed at the top of the rack and is positioned by the brake block device, the entire process is realized by cylinder, efficiency is high, and positioning is accurate; the rubber tyre is horizontally placed at the top of the rack, pressure is vertically applied to the rimmer by the rimmer pressing device, and the tyre is pressed out from the rubber tyre, the dismounting manner in the prior art is changed, the rimmer pressing device adopts hydraulic driving, pressure is large, and the rimmer can be rapidly pressed out from the rubber tyre; and the rubber tyre is pressed on the rack, the rimmer pressing device adopts a rimmer clamping ring to be touched with the rimmer, entire stress is realized when in pressure application, stress is uniformly distributed, and friction between the rimmer and the rubber tyre is reduced.