In order to realize the thermal protection of aluminum alloy structural materials in high temperature environment, the inorganic zirconium sol coating was prepared on the surface of aluminum alloy by sol-gel method. The stability of zirconium sol was prepared by using n-propanol zirconium and glacial acetic acid. The effect of PVP content on the size and viscosity of zirconium sol particles was studied. The mechanism of PVP on sol particles was analyzed. The inorganic coating was prepared by adding 60wt% SiO2, and the coating was ablated. The effects of different adhesives on the coating structure and thermal protection performance were compared. According to the macroscopic response and microscopic morphology of the coating in the ablation test, the thermal protection mechanism of the inorganic coating at high temperature was analyzed. The results show that the stability of zirconium sol is the best when the content of glacial acetic acid is 22wt%. After optimization of 7wt% PVP, the zirconium sol particles are uniform in size and have the best coating property. The silica sol-based coating has the best moldability. After the three kinds of adhesive coatings were ablated for 30s at 1300℃, the substrate was not broken, and the water glass-based coating peeled off after ablation; compared with other adhesive coatings, the zirconium sol-based coating had the best thermal protective ability. During the ablation process, the zirconium sol particles dehydrate and condense at high temperature to form nano-zirconia particles, which are dispersed around the filler and produce good synergistic heat insulation with the filler, so that the coating has good high-temperature thermal protection properties.