Given Hong Kong's coastal location and ample floating area, the establishment of a floating MiC (Modular Integrated Construction) factory is a viable solution to reduce the dependence on imported MiC modules from mainland China, which is necessitated by the high land costs in Hong Kong. The floating MiC factory's location can have varying degrees of societal and environmental implications. The study utilized the PESTEL-AHP method to ascertain the weights of the elements that influence the outcome and construct a mathematical model. The process involves utilizing GIS spatial analysis and AHP weighting criteria to produce thematic maps. These maps are then combined using weighted overlay to create a comprehensive map. The appropriateness index is then employed to identify the optimal location decision. According to the location selection research, the sea region to the west of Lamma Island is the top priority for location selection.