Hyper-cross-linked Polystyrene (H-PS) are prepared by an extensive post-cross-linking of linear polystyrene in solution or poly(styrene-co-divinylbenzene) in a highly swollen gel state using bifunctional alkylating agents in the presence of Friedel-Crafts catalyst. H-PS resins differ from conventional porous polymer materials due to their unusual pore structure and outstanding swelling performances in thermodynamically good and poor solvent. In this paper, recent studies progress of preparation, properties especially physical properties and various applications are presented.