Biological ion channels usually conduct the high-flux transport of 10 7 ~ 10 8 ions·s - 1 ; however, the underlying mechanism is still lacking. Here, by applying the KcsA potassium channel as a typical example, and performing multitimescale molecular dynamics simulations, we demonstrate that there is coherence of the K + ions confined in biological channels, which determines transport. The coherent oscillation state of confined K + ions with a nanosecond-level lifetime in the channel dominates each transport event, serving as the physical basis for the high flux of ~10 8 ions∙s - 1 . The coherent transfer of confined K + ions only takes several picoseconds and has no perturbation effect on the ion coherence, acting as the directional key of transport. Such ion coherence is allowed by quantum mechanics. An increase in the coherence can significantly enhance the ion conductance. These findings provide a potential explanation from the perspective of coherence for the high-flux ion transport with ultralow energy consumption of biological channels.