Thermal conductive graphite film is a multi-layer film composite material,and the in-plane thermal conductivity is its key performance parameter.The method of nondestructive testing based on heat flow loop integral relies on the thermal imager to measure temperature.However,the uncertainty transfer caused by the temperature measurement of thermal imager is not studied.By analyzing the temperature measurement model,it is proposed that the calibration of gain coefficient and the non-uniformity of bias coefficient are the main sources of uncertainty,and both of them are affected by time-varying characteristics.The experimental analysis of time-varying characteristics of thermal imager based on two constant temperature radiation sources shows that the gain coefficient is uniform and stable,and the offset coefficient is time-varying and non-uniform,which is the main source of uncertainty.Therefore,the measure of real-time bias coefficient correction using external cooperative blackbody in 20 s is proposed.After correction,the influence of nonuniformity of bias coefficient is reduced to 0.37 %,and the relative standard deviation of gain coefficient calibration result is 0.99 %.The uncertainty of the influence of temperature measurement on thermal conductivity is 1.03 %.This work can be used for reference in the uncertainty analysis of other quantitative thermal imaging applications.