A thin film strain gauge fabrication method was proposed based on high⁃temperature inorganic glue flattening treatment, magnetron sputtering technology and atomic layer deposition (ALD), aiming at solving the problem of high⁃temperature strain measurement on the surface of C / SiC composite materials. The surface of the C / SiC composite material was flattened by brushing inorganic glue, and then a thin film strain gauge consisting of a Pt sensitive layer and a composite insulating layer was prepared using magnetron sputtering and atomic layer deposition technology. Specifically, the Pt sensing layer was prepared by direct current (DC) sputtering through complex surface patterning technology with a hard⁃mask, achieving a resistance of 75 Ω and a thickness of 450 nm. For the insulating layers, three types of composite insulating layers (YSZ / Al₂O₃, Al₂O₃⁃YSZ / Al₂O₃, and HfO₂⁃YSZ / Al₂O₃ composite layers with a thickness of 1.2 μm) were prepared via DC sputtering and atomic layer deposition. A comparative study was emphatically conducted to evaluate the high⁃temperature insulation performance of the three insulating layers. The results indicated that the HfO₂⁃YSZ / Al₂O₃ composite insulating layer exhibited the best performance, with an insulation resistance of 32.94 kΩ at 950 ℃ after multiple thermal cycles. Strain testing under a temperature range from room temperature to 600 °C revealed that the Pt strain gauge fabricated based on HfO₂⁃YSZ / Al₂O₃ composite insulation layer achieved a maximum gauge factor (GF) of 2.93. The minimum and maximum measurement errors were 0.01% (600 °C, 133.2 με) and 6.49% (200 °C, 133.2 με), respectively. The strain gauge exhibited superior high temperature stability and strain response. The research results provide a new technical solution for high⁃temperature strain measurement on the surface of C / SiC composite materials, which possessed positive significance for promoting the development of high⁃precision strain measurement technology for thermal structural components of hypersonic vehicles.