A high temperature measurement method of bi-alloy of iridium and rhodium was put forward to solve the fracture problem of negative pole of conventional iridium-rhodium thermocouples. The experimental results on a high temperature calibration device show that the IrRh40-IrRh10 thermocouples have good linearity, and the sensitivity is about 3 uV/ C. An air temperature probe made by this type of thermocouples is suitable for measurement of high-temperature air flow in the engine development.