Abstract: The huge deep saline aquifer buried in Songliao sedimentary basin is a one of good geological media for CO2 geological storage. Reliable and reasonable estimation of CO2 storage capacity is an important factor for site selection and development. The universal pyramid method is introduced to assess the CO2 storage capacity for the sedimentary basin. The deep saline aquifer of Songliao basin is mainly made up of Cretaceous Nenjiang Group sandstone and Qingshankou Group sandstone. The saline aquifer has well developed porosity and the continuous sealing trap is overlying it. All of these determine that it can be used to CO2 storage. The pyramid method is applied to the deep saline aquifer of Songliao basin and the effective storage capacity of CO2 is about 6916Gt.