A staircase combination of the gang socket includes a plurality of integrally formed tubular sockets each having a bottom partially connected to the upper rim of the next socket and so on until a last socket partially connected its upper rim to the bottom of the socket positioned at above. Each of the sockets has a vertically cutting opening in a lateral side and closed by a plurality of integrally formed covers which are also connected partially their lower end to an upper end of the next covers, a common contact plate disposed between each of the adjacent sockets, a pair of single contact plate disposed within a first and last sockets opposite to the common contact plates and each connected with an electric wire, a plurality of lamps respectively inserted into the sockets.