Terahertz waves possess remarkable penetrability, capable of passing through a wide range of non-metallic, nonpolar materials without causing ionization. This unique characteristic makes them particularly useful in the field of computed tomography, enabling the capture of detailed external and internal structures of samples along their three-dimensional absorption coefficient distributions. In this process, the sinogram for each vertical layer is generated through raster scanning at different projection angles. These sinograms are then transformed into sectional images using filtered back projection and other algorithms based on the Fourier central slicing theorem. As the field has developed, a diverse array of illumination modes, imaging configurations, and reconstruction algorithms have been proposed. These advancements serve to accommodate the development of terahertz imaging instruments and components, as well as the expanding range of application scenarios. This study reviews the principals of terahertz computed tomography. We provide a comprehensive review of its recent research progress, focusing on enhancing three key areas: reconstruction quality, imaging resolution enhancement, and data acquisition efficiency.