Crude oil contains natural surfactants such as asphaltenes，resins，naphthenic acids，fatty acids，microcrystalline waxes， and interfacial active solid particles. During extraction，the shearing，compression and agitation within formation pores，wellbores， nozzles and pipeline valves，along with the addition of surfactants and water in oil displacement agents，as well as pump pressure and pipeline turbulence during collection and transportation，can easily form stable crude oil emulsions. Crude oil emulsions not only cause corrosion in pipelines and pumps and reduce pipeline transportation efficiency，but also lead to catalyst poisoning during downstream refining processes. Chemical demulsification，due to its high efficiency，rapid action，simple equipment requirements， and low energy consumption，is a commonly used method for the efficient separation of crude oil emulsions. Ionic liquids（ILs）are effective demulsifiers due to the advantages such as non-flammability，good thermal stability，recyclability，and low vapor pressure. By summarizing the characteristics of ILs and their current application as chemical demulsifiers，this paper discussed the demulsification mechanisms and factors influencing demulsification performance. It identified issues with the practical application of ILs demulsifiers，and then suggested future research directions. ILs were suitable for demulsification under harsh conditions such as high salinity，high temperature，and high viscosity（e.g. extra-heavy oil）. Demulsification mechanisms included adsorption， replacement and ion exchange. Factors affecting demulsification effect included the type and concentration of ILs，relative molecular mass，salinity，temperature，and emulsion type. By selecting appropriate ILs and their dosages，and determining optimum treatment conditions，demulsification efficiency could be enhanced. Although there were still significant challenges and key issues preventing large-scale application of ILs demulsifiers，the development of low-toxicity or non-toxic，low-cost， low-viscosity ILs and their use in conjunction with nanoparticles，and polymer ILs remained highly significant.