Abstract: Full polarization interferometric radiometer (FPIR), which combines the interferometric synthetic aperture imaging technology with full polarimetric information obtaining technology, is one of the most efficient ways in passive microwave remote sensing. It is difficult to obtain full polarization information for synthetic aperture interferometric radiometer. In order to obtain full polarization information and reduce the reconstruction bias, an improved reconstruction algorithm applied in FPIR system was presented, and the impact of cross-polarization on each component of full polarimetric brightness temperature was analyzed. The simulation results show that the improved reconstruction algorithm can greatly reduce the reconstruction bias, compared with conventional reconstruction algorithm. The improved reconstruction algorithm can obtain high accurate data of full polarimetric brightness temperature to meet the requirements of measuring soil moisture, sea surface salinity, sea surface wind vectors and so on.