In order to accurately measure the transient high temperature of propellant combustion, the measurement method of broadband thermal radiation temperature for propellant combustion was studied on the thermal radiation theory. The high temperature transient measurement system was integrated; the validity and reliability of the temperature measurement system were verified by single-base propellant combustion test under free-field conditions. Results show that the flame temperatures are between 1500 ℃ and 1800 ℃ when the samples of propellant are placed 3 m away, and the data are repeatable and coincide with theory.