Terahertz imaging technology has a wide range of applications in the fields of security screening, non-destructive testing, and medical imaging due to its unique properties. The terahertz band is located between 0.1 and 10 THz, and the wavelength is between 3 mm and 30 µm, which is not only safe for human body and biological tissues, but also has good penetrability to identify and analyze a variety of chemical substances. However, limited by the Rayleigh diffraction limit, the resolution of conventional imaging techniques is usually only accurate up to half wavelength of electromagnetic waves. To break through this limitation, an imaging system based on terahertz interference is designed and investigated in this paper. The construction of the reflective Michelson interferometric structure and the transmissive Mach-Zehnder interferometric structure and their applications in the terahertz frequency band are introduced in the paper. By using the reflective Michelson interferometric structure for imaging experiments with 1-mm resolution bars, the results show that the system is able to achieve an imaging resolution close to half-wavelength, with a contrast enhancement of about 50% compared to the non-interferometric system, and a more pronounced gap between the resolution bars. In addition, the feasibility and advantages of this new system are verified by building a transmission Mach-Zehnder interferometric system for imaging experiments on a hollowed-out steel plate. Although the half-wavelength resolution is not achieved, the difference of the two-optical paths effectively reduces the phase noise and improves the imaging quality.