A new method of polarization imaging, based on Stokes parameter, is proposed by digital in-line holography. The idea is to reconstruct the spatial distribution of polarization state of light transmitted through anisotropic objects using a linearly polarized beam and an elliptically polarized reference beam. Stokes parameters of object wave are obtained and the distribution of polarization can be determined uniquely by obtaining digital holograms in both orthogonal orientations and measuring the information about amplitude and phase of object wave in these two directions. The results show that the method can be used to measure the polarized properties of objects. In addition, it is applicable to both in-line and off-axis holography, because it can remove a zero-order and conjugate image components while acquiring Stokes parameters of object wave.