When in contact with liquid electrolyte under working conditions, the electrode materials will attract counter-ions from the solution and form the electric double layer (EDLs) that strongly modulates the interfacial reactivity and wetting. EDLs can be developed either at metal electrodes beyond the potential of zero charge or at metal-oxide electrode outside the point of zero charge. In the latter case, the metal-oxide surfaces are positively or negatively electrified by the adsorption of protons and hydroxyl groups, which depend on the pH of the environment. The well-known classical Gouy-Chapman-Stern (GCS) model has been used to describe the EDLs structure at oxide surfaces, in which EDLs consist of a space charge layer, Helmholtz layer and Gouy-Chapman layer. The Helmholtz layer is formed by the interfacial proton charges and counterions from the electrolyte, which spans for 3-5 Å. The microscopic structure, in particular, the fully solvated surface and the interaction and orientation of adsorbed or dissociated water molecules, and differential capacitance of Helmholtz layer greatly determine the electrochemical performances, i.e., the thermodynamics, kinetics, and product selectivity of electrode materials. Therefore, the description of the relationship between water adsorption energy E ads and EDLs is crucial. Thanks to the development of advanced in situ experimental technologies and theoretical studies, it is not until recently that the structure and properties of interfacial EDLs have started to be revealed. For example, the electrochemical Xray photoelectron spectroscopy (EC-XPS) applys to the char-acterization of the surface structure of the electrode, sumfrequency vibrational spectroscopy retrieves the vibrational spectra of the bonded water layer and the ion diffuse layer, in situ Raman spectroscopy investigates the interfacial water on single-crystal surfaces, dual scale atomic force microscopy (AFM) spectroscopy technique provides a direct access to the facet-dependent local surface charge density and potential drop across the diffuse part of the EDL, operando scanning electrochemical probe microscopy can correlate electrochemical activity with changes in surface properties. Moreover, various computational methods, e.g., quantum mechanics/implicit solvation model(QM/ISM) , quantum mechanics/molecular mechanical(QM/MM), density functional theory-based molecular dynamics simulation (DFTMD) and machine learningaccelerated MD simulations have been employed to simulate the electrochemical interfaces and describe the microscopic structure and the dynamics of water and ions near the interfaces.