Abstract: The principle of semi-natural thermocouple to measure the temperature was introduced and the semi-natural thermocouple was calibrated with good linearity.Radial friction welding process was carried out with the relf-design radial friction welding machine.Based on the friction welding process characteristics, the appropriate thermometer and thermocouple were selected.The temperature on the friction interface was tested with the semi-natural thermocouple.The points on different distance from the interface were measured with K type thermocouple.The temperature on the friction interface rises quickly and there is an obvious stage with constant temperature.With the increase of distance from friction interface,the rising rate of the temperature decrease gradually.After the welding process,the temperature gradually tends to be homogenous.