Abstract: A double hot-wire method is adopted to separate the mixed signal of temperature fluctuation and velocity fluctuation appearing in high temperature turbulences. The relationships among the various coefficients in the sensitivity equation for measuring turbulent fluctuations with constant temperature hot wire anemometer are deduced. Once these equations are being related to the temperature fluctuation sensitivity equation of a constant current hot wire anemometer, the temperature fluctuation signal may be taken out from the mixed signal, then the turbulent velocity fluctuation signal and other main turbulent parameters may be obtained.