The seismic hazard environment and associated vulnerability of urban buildings are key factors affecting the seismic ability of buildings with complex networks under strong earthquakes. However, evaluating the seismic capacity of buildings is problematic because pre-assessment results are not adequately accurate, and it is only possible to determine the degree of damage using a damage assessment after the building has been destroyed by an earthquake. This study proposes a seismic capacity evaluation method for buildings with complex networks. In consideration of risk factors affecting buildings during earthquakes, peak ground acceleration is used as a parameter to evaluate and analyze the invulnerability of complex building networks under strong earthquakes. In addition, seismic ability indexes are proposed to evaluate the seismic performance of complex building networks. The seismic capacity level is then obtained using seismic capacity assessment criteria, and simulation experiments are conducted. The effectiveness of the proposed method is also confirmed using data of actual earthquake damage.