In order to optimize the two-dimensional Fourier transform demodulation in spatially modulated full polarization imaging system， Bessel's correction directional selective two-dimensional Hanning apodization optimal demodulation algorithm is proposed. The characteristics of main lobe width and sidelobe attenuation of different apodization functions are compared and analyzed. Compared with the traditional Hanning window， the proposed algorithm has a sidelobe suppression capability improved by 12.89 dB and a main lobe width of 0.065π. At the same time， it shows a good suppression effect on the diagonal spectrum information of the relative position in the spectrum filtering process. A system imaging simulation platform based on Jones matrix is built and verified by experiments. The experimental results show that the full polarization component demodulation accuracy of the optimized demodulation algorithm is improved by 9.48% on average， which verifies the accuracy and effectiveness of the optimized demodulation algorithm.