Based on the beam coherence-polarization matrix and Collins formula, Compared with previous results, the evolution relationship from near-field to far field of the on-axis and on- radial polarization properties of Gaussian Schell-model beams diffracted through a rectangular aperture are studied numerically. It is shown that, as diffraction effect, the polarization distribution of Gaussian Schell-model beams becomes non-uniform, there are oscillations of the on-axial and on radial polarization distribution, with increasing of the truncation parameter and decreasing of spatial coherence parameters and transmission distance, Oscillations strengthen gradually. When the beams upon free space transmit on axis, polarization distribution in the near field is uniform, as same as that of source plane, with increasing of transmission distance and decreasing of spatial coherence parameters. The on-axial polarization distribution increases, there are no oscillations.