Structure and function of gap junction as well as the role of pH_i, voltage and cytokines on the modulating of gap junction are introduced. Gap junction is an information channel between the adjacent cells, with the function that delivering message and coordinating the actions of cell groups, but its formation and its function on the physical events need more research. The lower pH_i closes the gap junctional channel and it is explained by “particle-receptor” model. The increase of voltage downregulates the conductance of the channel. Cytokines regulate the permeability of gap junction by changing the synthesis and degradation of connexin, enhancing the phosphatizing the connexin.