We present an overview of recent progress of T-ray imaging. Compared with microwave, X-ray imaging and NMR (nuclear magnetic resonance), T-ray imaging can give us not only the density picture but also the phase information within the frequency domain. The unique rotational, vibrational and translational responses of materials (molecular, radicals and ions) within the THz range provide information that is generally absent in optical, X-ray and NMR images.The important characteristic of T-ray is that it has potential to detect the nature of low energy processes in physics, chemistry and biomedicine without the ionization. T-rays can also easily penetrate and image inside most dielectric materials, which make it a useful and complementary imaging source.