Abstract: The image inversion is a key issue to synthetic aperture radiometer.The generally used inversion algorithm is the G matrix model，in which there exists a large reconstruction bias.In order to reduce the reconstruction bias，a resolving matrix approach is introduced and simplified for full polarization interferometric radiometer(FPIR)system.The simulation results show that the simplified resolving matrix approach can greatly reduce the reconstruction bias，compared with conventional G matrix model.It is demonstrated that the simplified resolving matrix approach is effectively applied in the FPIR.