This work established an evaluation index system based on a comprehensive analysis of those factors affecting the suitability of CO2 geological storage. This evaluation index system includes three evaluation index layers of geological safety, storage scale and social economy, nine evaluation index sub-layers, and 28 evaluation index factors, and adopts the analytic hierarchy process (AHP) and index overlay methods. Taking the Xining Basin in northwest China as an example, we conducted comprehensive analysis of geological conditions and performed quantitative evaluation based on this evaluation index system, which indicates that the Shuangshu depression of the Xining Basin is comparatively suitable for CO2 geological storage. It is suggested that this evaluation index system and the evaluation method proposed in this study are suitable for most continental sedimentary basins in China and should be widely applied.