Large conductance Ca²⁺ activated potassium channel (BK) is the only ion channel which is regulated by intracellular Ca²⁺ and membrane potential in the cell membrane. Recently the structure of BK determined by cryo-electron microscopy (cryo-EM) shed the first light on the assembly of the whole channel, as well as the crystal structure of the cytosolic domain by x-ray single crystal diffraction. In addition, these 3D structures corroborate many close interactions among these domains during channel gating. More recently, great advancements have been made in the research on functional regulation and gating kinetics simulation of BK channels, these contribute to understand the gating mechanism of the BK channel and the pathophysiological basis of BK-related ion channel diseases.