Abstract: The enhancement of ionospheric total electron content(TEC)caused by auroral activity will have a significant impact on the L-band electromagnetic wave signal emitted by the spaceborne fully polarimetric synthetic aperture radar(SAR)system,resulting in additional phase error and polarization distortion.By solving the Faraday rotation angle(FRA)in the signal,the high-precision and high-resolution ionospheric TEC variation characteristics can be retrieved.In this paper,31 scenes of fully polarimetric SAR image data are used to calculate the polar ionospheric TEC using four typical FRA inversion algorithms,and the results are compared with the local ground-based GNSS-TEC observation results.The influence of auroral activity on SAR signal quality is quantitatively analyzed.The results show that among the four algorithms used,the polar TEC obtained by the B&B algorithm is the most consistent with the observed value.The TEC enhancement caused by the auroral arc will significantly affect the SAR signal,making its FRA significantly increased,while the cross-circular polarization product is reduced,that is,the signal-to-noise ratio is reduced.The research shows that the fully polarimetric SAR based on B&B algorithm can effectively invert the polar TEC,which provides a new technical means for studying the polar ionospheric TEC disturbance and its relationship with auroral activity.