Gating in ion transport is at the center of many vital living-substance transmission processes, and understanding how gating works at an atomic level is essential but intricate. However, our understanding and finite experimental findings of subcontinuum ion transport in subnanometer nanopores are still limited, which is out of reach of the classical continuum nanofluidics. Moreover, the influence of ion density on subcontinuum ion transport is poorly understood. Here we report the ion density-dependent dynamic conductance switching process in biomimetic graphene nanopores and explain the phenomenon by a reversible ion absorption mechanism. Our molecular dynamics simulations demonstrate that the cations near the graphene nanopore can interact with the surface charges on the nanopore, thereby realizing the switching of high- and low-conductance states. This work has deepened the understanding of gating in ion transport.