Abstract: This paper introduces the selection process for the site of a segment prefabrication factory for the immersed tunnel of the Hong Kong-Zhuhai-Macao Bridge Project (HZM Bridge). The proposed sites for the prefabrication factory were Longxue Island and Guishan Island. This paper explicates the factors used in site selection, including a survey of the prefabrication factory, work flow, and the importance to the HZM Bridge. Based on a comparison of their geographic positions, transportation conditions, and existing problems regarding geology and geotechnical engineering. Guishan Island was chosen as the site of the segment prefabrication factory.