Terahertz radiation can penetrate through most non-conducting materials. Imaging with terahertz waves for these materials could provide an appropriate contrast compared with infrared, visible light and X-ray. Edge diffraction in terahertz pulsed imaging (TPI) enables the image contrast to be further enhanced, which exhibits considerable application potential to recognize shape features in the sample under test, especially for those weak absorption materials. In this report, we perform a theoretical investigation on the edge diffraction effect and present a diffraction enhanced imaging method based on pulsed terahertz radiation without modification of the conventional TPI system. Experimental results demonstrate the capability of our method for image quality improvement. ©2009 IEEE.