Abstract: Coal gasification crude slag can be used as a precursor to prepare geopolymer, and its high temperature resistance needs to be further explored. In this paper, geopolymers prepared by mixing 10% of TiO₂, 30% of fly ash and 30% of slag in coal gasification crude slag were treated at high temperature, and the thermal stability of four 28d geopolymers at different temperatures was explored. The results show that at 100 ℃, the compressive strength of the sample is not much different from that at room temperature. At 200 ℃, 400 ℃ and 800 ℃, the compressive strengths of the four samples all decreased to different degrees. The strength attenuation is most obvious in the samples doped with mineral powder, and the strength attenuation of the samples doped with TiO₂ is smaller at high temperature. With the increase of temperature, the geopolymers cracked: at 100 ℃ and 200 ℃, only the coal gasification coarse slag geopolymers cracked; at 400 ℃, the geopolymers only mixed with TiO₂ did not crack; at 800 ℃, all geopolymers cracked. Geopolymers doped with TiO₂ have better high temperature resistance due to the anatase content.