In order to achieve nondestructive testing and imaging of phase objects, and overcome the problems existing in eliminating the interference of zero-order diffraction and conjugate image in phase objects imaging technology by in-line digital holography, a new digital holography method with polarization detection is proposed. Two beams, a reference wave with a horizontal polarization state and an object wave with a vertical polarization state, are synthesized. Using polarization detection method to measure the Stokes parameters of synthesized beam, amplitude and phase difference information of these two beams is obtained. Then a virtual image which contains the information of object beam is constructed. The amplitude and phase information of the object is obtained without removing the zero-order and conjugate image components. In the experiments, a phase object with weak absorption is measured and clean reconstructed images are achieved, including the distributions of amplitude and phase. It is shown that the serious interference of the noise in conventional hologram, the zero-order diffraction and conjugate image can be overcome by applying this algorithm, and it is feasible and effective to extract amplitude and phase information of phase objects.