CO2 leakage is a fatal issue for the successful application of CO2 geological storage. In this paper, a method using CO2 triggered gelation is proposed to control the CO2 leakage during CO, geological storage process. The mechanisms of CO2 triggered gelation was illustrated schematically. The effectiveness of this method for blocking CO2 leakage was evaluated by experimental works using sand-pack model. Reactive flow simulations were conducted to reproduce the experimental results and investigate field-scale feasibility of this method. The results show that this method can control the assumed leakage and the blocking performance was reproduced well by the lab-scale reactive flow simulation model. The results of simulation indicate that gel can be formed and absorbed more easily near the injection point. Feasibility of this method in field-scale were demonstrated with different scenarios of preplaced gel system. Infill drilling and monitoring method with high accuracy are recommended to assist this method.