A touch projection system includes a screen, an image-capturing device, a micromirror device, and a TIR prism disposed in front of the micromirror device. The TIR prism includes an optical path compensation structure or a hollowed channel, so that an image light from the screen, traveling through the TIR prism to be reflected by the micromirror device, can travel through the optical path compensation structure or the hollowed channel to avoid a probable optical path difference on the image light due to traveling through the TIR prism. Thereby, the invention can solve that a distortion may be induced in a touch image formed by the image-capturing device receiving the image light reflected by the micromirror device.