This paper describes the calculation of the errors of various sensors for duct airflow temperature measurement on the basis of the problems encountered in application, and the quantitive analysis of the errors of the temperature sensors of resistor and thermocouple types. Because of the significant defects of the temperature sensors with sealed housing in practical use,it is suggested to use thermocouples for the measurement of duct airflow temperalure in aircraft environment control system (ECS). Also, this paper provides the structure of a practical temperature thermocouples and points out how to reduce the error caused by thermal conduction and radiation.