Geological CO2 storage involves injecting captured CO2 into various geological formations, in which saline aquifers have the largest storage potential around the world. In the context of carbon neutrality, one of the key issues is to store CO2 as much as possible on the premise of formation stability. In this paper, we find that external electric field can enhance CO2 storage in saline aquifers. The different mechanisms of CO2 storage enhancement in hydrophobic and hydrophilic formations are revealed by molecular dynamics simulations. The hydrogen bonds are analyzed to reveal the different enhancement mechanism. In the hydrophobic formations, the electric field can decrease the number of hydrogen bonds between H2O molecules. Meanwhile, CO2 desorbs from the rock surface and enters the aqueous phase, resulting in an increased degree of dissolution rendering the initially hydrophobic wall hydrophilic, thereby reducing the available space for adsorbed CO2, and promoting its dissolution in the H2O phase. In the hydrophilic formations, the external electric field drives H2O away from the surface, concurrently reducing the number of hydrogen bonds formed between H2O and the hydrophilic wall. This reduction diminishes the hydrophilicity of the wall. This study proposes a novel technique to enhance CO2 storage in saline aquifers of different by electric field. The molecular perspective revealing the enhancement mechanism is expected to provide theoretical guidance in the future practical application.