A conductive rail joint comprises a left conductive rail (1), a middle rail (2), a right conductive rail (3), supporting plates (4), electric conductors (5) and conductive wires (6). The opposite end faces of the three rails are slant and parallel with each other. The supporting plates (4), the electric conductors (5) and the conductive wires (6) respectively consist of a left one and a right one. The two supporting plates are axial non-symmetrically mounted at the bottom of the corresponding conductive rails (1, 3) respectively. One end of each electric conductor (51, 52) is fixed to the corresponding supporting plate (41, 42) and the other end is suspended. Each of the two conductive wires (61, 62) is connected between the fixed end of the corresponding electric conductor (51, 52) and the suspended end of the other electric conductor (52, 51). The conductive wires (6) are loose after the connection. The conductive wires (6) and the electric conductors (5) consist of a loop so that when the conductive rails are expanded or contracted, the longitudinal displacements of the two conductive rails are not restricted.