Through extensive and systematic reviewing of literatures, this paper presents some thoughts on the existence of ion and water channels in highly dense and well-ordered CH 3 -terminated alkanethiol self-assembled monolayers (C n SH-SAMs) on gold: (1) based on the combinational effect of “the van der Waals interaction between the neighbor hydrocarbon chains”, “the framework size of C n SH molecule” and “the surface lattice structure of C n SH-SAMs on gold”, a simple ideal model of the close-packed C n SH-SAMs is proposed for the first time. The channel with an appropriate diameter of about 3Å (∼3Å) existing in SAMs on Au is deduced, which is found large enough for ions and water molecules to permeate; (2) through summarizing the literature reports for various experiments (e.g. scan microscopy techniques and electrochemical methods, etc.), the existence of the ion and water channels (∼3Å) in close-packed C n SH-SAMs is verified; (3) furthermore, the effect of the ions and water molecules permeation on the studies of the SAMs’ electron tunneling process is discussed. This simple ideal model of the close-packed C n SH-SAMs established by us may clarify the controversies about the permeation mechanism of ions and water molecules in C n SH-SAMs.