Based on years of theoretical and experimental research on prefabricated underground structure construction technology, the design technology and methods of prefabricated underground structures for urban rail transit and other municipal engineering projects under opencut conditions are systematically summarized through practical engineering applications. The research contents include: (1) Basic design principles and regulations of prefabricated underground structures are put forward based on aspects of industrial construction concepts with full omnibearing of prefabricated technology, and the main design contents are described and combined with the characteristics of opencut prefabricated structures. (2) Important links of prefabricated structure design are discussed, including the determination of structural system, foundation pit engineering, and structure waterproofing; the design methods of joint selection, structure separation, and internal structure, as well as the technical requirements and design methods of foundation pit engineering design based on prefabricated structures are summarized, which covers the selection of the support, the determination of the width of the foundation pit, the technical design of the pile wall + internal support system, the design of the foundation pit backfill technology, etc. Moreover, the key waterproofing technologies of prefabricated underground structures are summarized.