Ultraviolet(UV) irradiation technology can improve indoor air quality and control microbial contamination in pipelines. This article reviews the mechanism of UV irradiation for killing airborne microorganisms (DNA damage, lipid changes and protein damage), factors affecting the effectiveness of UV removal of microorganisms inside pipelines, calculation models of UV intensity distribution inside pipelines, and theoretical models of UV in killing microorganisms. It also provides an outlook on the future research direction of UV irradiation for removing air-borne microorganisms in pipelines.