In recent years, poly(ionic liquid)s (PILs) have received extensive attention because of their advantages in mechanical stability, processability, ionic conductivity and chemical compatibility. Firstly, the classification and synthesis methods of PILs are introduced. And then, the applications in the fields of adsorption and separation are reviewed. Moreover, The development of poly(ionic liquid)s is prospected. The important development direction is to study the structure-properties relationship, synthesize new poly(ionic liquid)s, and expand their applications in future research of poly(ionic liquid)s.