methods [5f ] or by using emerging sub-nanometer porous materials to split large nanochannels [14e,49] and nanopipettes [15a,44a] into multiple sub-nanometer pores or channels. Single-ion selectivity [5f ] has been mainly achieved in sub-1 nm pores with specific ion-binding sites (Figure 1L). At present, a series of artificial single-H + , [19a,50] K + , [51] Li + , [42d,49c,52] Na + , [15c] F − , [14f,53] Cl − , [54] and I −[25b] selective ion channels have been developed to mimic the nature ion channels.To achieve accurate measurement of these unique selectivities in nanofluidic devices, different advanced experimental methods have been developed. For example, drift-diffusion experiment with the Goldman-Hodgkin-Katz (GHK) model [6a,14b,15b,19b,32d,44a,55] and charged molecule permeation experiments [56] have been developed for measuring the charge selectivity of nanofluidic channels and membranes. Ion permeation (diffusion) experiment, electrodialysis, ion current/ conductance/conductivity measurements, and pyranine assays were developed for investigating mono/divalent ion selectivity of nanofluidic devices. Notably, the drift-diffusion experiments, ion permeation (diffusion) experiments, conductance/conductivity measurements, and pyranine assays could also be used for single-ion selectivity measurements. Herein, in this review, research progress to date on investigations of the selective transport properties of the nanofluidic devices is reviewed. We begin by briefly reviewing some of the advanced construction strategies of nanofluidic devices that enable the measurement of their ion transport properties. We also summarize recent advances in experimental methods and theories for ion selectivity measurements and calculations. This is followed by a discussion of the challenge and future development of ion selective nanofluidic devices.