Abstract: The charge transport properties of dielectrics determine spacecraft charging level and electrostatic discharging（ESD） probability,affecting the reliability and lifetime of spacecrafts.To investigate the charge carrier mobility of space grade polyimide at various temperatures,a novel method based on Thermally Stimulated Current（TSC） is proposed in present paper.Charges will inject from the electrodes into the material after a high voltage is applied for a while,and been maintained in the traps when the material is frozen with liquid Nitrogen.The trapped charges in the insulator are assumed to satisfy Boltzmann distribution.When the temperature of the sample is increased slowly,the trapped charges will gradually detrap to the conduction band and transport to the contacted electrode.Based on this physical model,we can derive the charge carrier mobility from TSC.We calculate the temperature dependent charge carrier mobility of polyimide film at the temperature range of 173 K~493 K.These results are compared with that measured by space charge limited current method,and they are in good agreement with each other.It may provide an efficient way to study the charge transport characteristics of insulators and help spacecraft engineers better the design of spacecraft shielding.