Compared with traditional cast-in-place structures, fabricated structures have the characteristics of saving energy, protecting the environment, eliminating mold, and short construction times. Fabricated structures have been developed rapidly in above-ground buildings. However, the use of underground fabricated structures in China has only recently begun. Owing to the complexity of the underground environment, waterproofing underground fabricated structure joints remains a problem. In this paper, based on an analysis of the joints of an underground fabricated building and of the current state of waterproofing technology, we propose the use of an epoxy grouting material, which is used to pot the prefabricated structure joint, and study the mechanical properties of the epoxy grouting material and its bonded concrete. At the same time, we introduce backfilling technology for prefabricated solidified soil in the foundation pit, and expound the effect of the prefabricated solidified soil on the waterproofing of the underground engineering structures. The research results are good references for similar engineering projects.