Abstract: Safety and storage performance are the most attracting issues for geological CO₂ storage (GCS), in which the site uncertainties caused by faults/fractures are complex. Based on the reservoir multiphase flow simulator TOUGH2/ECO2N, the time, the CO₂ leakage rate and the amount of leakage from the deep saline aquifer along the fault were studied under various conditions. The results of 15 site-scale models show that the CO₂ injection scheme, fault properties (location, occurrence, geometry, and structure) and the combination of rock formations in the system have effects on CO₂ leakage. Under the same reservoir environment and fault occurrence conditions, the CO₂ injection rate increases from 1.59 kg/s to 6.34 kg/s, the CO₂ leakage occurs 3 706 days earlier and the leakage amount increases by 32.43% in 20 years. The effect of fault location on CO₂ storage is significant. In this study, a fault located at 100 m from the injection well will cause the CO₂ leakage to be as high as 63.39% of the injection after 20 years. Under the same conditions, the inclination/narrow faults have less effect on the leakage of CO₂ and brine than the vertical/ thick faults. An increase in the fault permeability by one time can lead to the leakage of CO₂ to increase by 2.11% and the leakage rate to increase by 0.006~0.01 kg/s.