Ions at the oil-water interface is a ubiquitous phenomenon which plays a important role in many industrial processes, such as extraction separation, nanoparticle assembly, enhanced oil recovery, etc.In the petroleum industry, due to the long-term interaction with solids and crude oil, the water including formation water, injection water and aqueous solution dissolves lots of ions, such as Na+, K+, Ca2+, Mg2+, Cl-, SO42-, etc.The migration of charged ions in the bulk phase or interface between oil and water has a significant influence on the molecudar packing of active species at the interface, zeta potential of oil droplets and microstructure and strength of interfacial film by changing the interfacial tension, interface viscosity and electrical repulsion of charged ganglia, thus affecting the stability of crude oil emulsions and the oil displacement in porous media.Consequently, more detailed knowledge of how ions affect the properties of oil-water interface is required.