In this paper, air plasmas spray(APS) was used to prepare YSZ and Sc2O3–YSZ(Sc YSZ) coating in order to improve the thermal insulation ability of TC4 alloy. Si O2 aerogel was also synthesized and affixed on TC4 titanium alloy to inhabit thermal flow. The microstructures, phase compositions and thermal insulation performance of three coatings were analyzed in detail. The results of thermal diffusivity test by a laser flash method showed that the thermal diffusivities of YSZ, Sc2O3–YSZ and Si O2 aerogel are 0.553, 0.539 and 0.2097 10 6m2/s, respectively. Then,the thermal insulation performances of three kinds of coating were investigated from 20 1C to 400 1C using high infrared radiation heat flux technology. The experimental results indicated that the corresponding temperature difference between the top TC4 alloy(400 1C) and the bottom surface of YSZ is 41.5 1C for 0.6 mm thickness coating. For 1 mm thickness coating, the corresponding temperature difference between the top TC4 alloys(400 1C) and the bottom surface of YSZ, Sc YSZ, Si O2 aerogel three specimens is 54, 54.6 and 208 1C, respectively. The coating thickness and species were found to influence the heat insulation ability. In these materials, YSZ and Sc YSZ exhibited a little difference for heat insulation behavior. However, Si O2 aerogel was the best one among them and it can be taken as protection material on TC4 alloys. In outer space,Si O2 aerogel can meet the need of thermal insulation of TC4 of high-speed aircraft. In this paper, air plasmas spray (APS) was used to prepare YSZ and Sc2O3-YSZ (Sc YSZ) coating in order to improve the thermal insulation ability of TC4 alloy. Si O2 aerogel was also synthesized and affixed on TC4 titanium alloy to inhabit Thermal flow. The microstructures, phase compositions and thermal insulation performance of three coatings were analyzed in detail. The results of thermal diffusivity test by a laser flash method showed that the thermal diffusivities of YSZ, Sc2O3-YSZ and Si O2 aerogel are 0.553, 0.539 and 0.2097 10 6m2 / s, respectively. Then, the thermal insulation performances of three kinds of coating were investigated from 20 1C to 400 1C using high infrared radiation heat flux technology. The experimental results indicated that the corresponding temperature difference between the top TC4 alloy (400 1C) and the bottom surface of YSZ is 41.5 1C for 0.6 mm thickness coating. For 1 mm thickness coating, the corresponding temperature difference between the top TC4 allo ys (400 1C) and the bottom surface of YSZ, Sc YSZ, Si O2 aerogel three specimens is 54, 54.6 and 208 1C, respectively. The coating thickness and species were found to influence the heat insulation ability. Sc YSZ exhibited a little difference for heat insulation behavior. However, Si O2 aerogel was the best one among them and it can be taken as protection material on TC4 alloys. In outer space, Si O2 aerogel can meet the need of thermal insulation of TC4 of high-speed aircraft.