Situations in which deep excavations are made adjacent to metro stations in service are common in the development of underground space. However, the structural responses of existing metro stations to adjacent deep excavations and their safety criteria are still not fully understood. Through a series of numerical parametric studies and comparisons with case histories reported in the literature, this paper examines both the structural forces and differential displacements of existing metro stations induced by adjacent excavations. To consider the effect of stress history, the hardening soil small-strain model (HSS) was employed, and the building process of existing metro stations was included in the numerical simulations. The effects of key factors, e.g., the distance between existing metro stations and new excavations and the depth of new excavations, governing the responses of existing metro stations to adjacent excavations are investigated and quantified. In addition, the barrier effects of exist...