We introduced two continuous-wave terahertz iterative phase-contrast imaging methods. In-line digital holography has the capability to reconstruct the amplitude and phase distributions simultaneously. It is a non-destructive, high-resolution, full-field dynamic phase-contrast imaging technique. Ptychography can reconstruct the complex amplitude distribution of the transmission object from the overlapped diffraction patterns. Both methods can achieve phase-contrast imaging, and are suitable for terahertz region. In this paper, both Gabor in-line holographic and ptychographical configurations are investigated from algorithms to experiments. For in-line holography, the use of extrapolation, synthetic aperture, sub-pixel shifting and multi-plane imaging are introduced to improve the resolution and reconstruction accuracy. For ptychography, we obtained the ptychographical reconstruction results of a polypropylene alphabet sample, which provides a new imaging method for terahertz phase-contrast imaging.