Terahertz imaging technology has shown great application potential in the fields of safety inspection and medical imaging. Compared with traditional mechanical scanning imaging and focal plane array imaging, single-pixel imaging has the advantages of simple system, fast imaging speed, and low cost. By combining spatial light modulation technology, the two-dimensional terahertz spatial information of the target can be reconstructed by using the association algorithm. Starting from the basic concept and development process of terahertz single-pixel imaging, this paper focuses on the principle, materials, development applications, and possible challenges of coding masks in single-pixel imaging.