Abstract: Temperature parameter is an important aspect of the combustion stability test for aeroengines. Compared to other temperature measurement methods, ultrasonic temperature measurement based on single crystal oxide offers advantages such as a wide range and good stability. Firstly, the sensor parameters are analyzed and designed, sound wave transmission and the working state of the sensor under different diameters and curvatures of the convex section structure are simulated with COMSOL. The simulation results demonstrate that the convex section structure exhibits a strong sound-temperature relationship. Secondly, the ultrasonic temperature sensor that consistent with the simulation parameters is fabricated using sapphire acoustic waveguide grown by laser heated pedestal growth, and a temperature measurement system is accordingly established. Static calibration is conducted in a high-temperature furnace with a working temperature of 1 600 ℃. The test results confirm that the sensor can operate continuously for 5 h in high-temperature environments with repeatability at 95.43% and unit sensitivity ranging from 12.57 to 35.72 ns·(℃·m)⁻¹. In comparison to laser etching’s “groove” structure, this new “convex section” structure demonstrates improved structural stability and oxidation resistance, making it better suited for high-temperature testing. It provides a method for monitoring temperature environments and conducting structural research on new materials.