In this study, we developed a new flow pump permeability test to investigate the behavior of CO 2 injected into low permeable rocks. The injection of supercritical CO 2 was conducted on a cored sandstone saturated with water. In addition, numerical analysis of flow pump permeability test incorporating Darcy's law for two phases flow analysis was developed in order to determine the relative permeability of saturated water and of CO 2 as well as the specific storage of the core during CO 2 injection. To examine the effect of CO 2 state, the injection of liquid CO 2 was also undertaken. It was observed that the injection of CO 2 in liquid state is able to drive more CO 2 flowing through the core, yet also generate a higher hydraulic pressure in comparison to supercritical CO 2. The migration of supercritical CO 2 in low permeable rocks within low gradient hydraulic will take very long time and indicates supercritical state becomes the appropriate state of CO 2 in a long-term sequestration.