The invention provides a composite segment, which comprises two concrete structures arranged on both sides along the longitudinal direction and a steel structure arranged between the two concrete structures. A connecting piece is fixed at the interface between the steel structure and the concrete structure for connecting the concrete structure and the steel structure, and the concrete structure isthe ring-directional joint of the composite segment; the two concrete structures are both machinable concrete structures, one of the two concrete structures is formed into a tenon, and the other concrete structure is formed into a blind mortise, wherein the shapes and sizes of the tenon an the blind mortise are matched with each other, which makes the adjacent composite segments matched with eachother through the tenon and the blind mortise. According to the invention, by utilizing the concrete structure instead of the steel pipe sheet tenon and blind mortise, not only the good performance of compression, bending and shear resistance can be guaranteed, but also the production cost can be effectively reduces.