The action from high temperature on the signal transmission line can result in some uncertainty on the test signal in the measurement process.According to this problem

a thermal-electric coupled method is proposed to investigate the temperature evolution of conductor and the stability transmission of electric signal affected by high temperature.Based on above analysis

a biased error formula is put forward to estimate the relation between input and output signal.The coupled physics field model is established by using the finite element method.The discussion is also developed on the common action from the heat convection between transmission line and external environment and Joule heat generated with the transmission of electric signal.And then the main factors affecting the stability transmission can be obtained on the basis of certain thermal-electric theory and simulation analysis.This analytical method and conclusion can be used to improve the measurement precision of the high temperature test and has certain guiding sense for the practical engineering.