Abstract: It is the basis for a reliable result to consider the uncertainties in all aspects of seismic risk assessment scientifically and reasonably. This paper established a seismic risk assessment model in which the uncertainties of seismic hazard and structural vulnerability are taken into account comprehensively. In this model, the uncertainty of seismic hazard assessment (SHA) was discussed by using the data of earthquake safety evaluation for engineering sites in a city. Meanwhile, the impact of ground motion uncertainty on structural vulnerability of urban building complexes (UBCs) were analyzed on the basis of the basic structure classes (BSCs) of UBCs. Based on the above study, the mean-annual-exceeding probability and the earthquake risk probability within 50 years at different damage state thresholds of the urban BSCs were obtained. Moreover, the seismic economic loss risk curve for each BSC was drawn according to the loss ratios corresponding to different damage state thresholds. Finally, the general seismic economic loss risk curve for UBCs in a city was combined by using control points with equal probability in each curve of individual buildings, which provided a reference for assessing the seismic risk of UBCs.