Superconductivity is a peculiar quantum phenomenon which originates from the pairing of conduction electrons, tbllowed by phase coherent condensation, Since the discovery by K. Onnes in 1911, superconductivity has been one of the hottest topics in physics for an entire century, and still attracts people＇s great interest. One of the intriguing issues is how superconductivity appears in low dimensional system where quantum size effect and surface/interface effect that large bulk material doesn＇t have may become crucial.