The invention discloses a sliding board of a composite structure and belongs to the technical field of metallurgy continuous casting equipment. The sliding board is used in a steel ladle sliding nozzle system and comprises an outer shell, an expansion layer, a wear-proof lining, an upper adhesion layer, a lower adhesion layer, a left board brick and a right board brick. The upper surface of the left board brick and the upper surface of the right board brick are located on the same plane. The left board brick and the right board brick are spliced to form a sliding board body. A complete conic hole of the sliding board body is formed by a semicircular conic hole of the left board brick and a semicircular conic hole of the right board brick. A cylindrical hole is formed in the center of the wear-proof lining and serves as a casting opening. The upper adhesion layer is located between the conic hole of the sliding board body and the wear-proof lining, the lower adhesion layer is located between the lower surface of the sliding board body and the outer shell, and the expansion layer is located between the periphery of the sliding board body and the outer shell. The sliding board of the composite structure has the advantages that the sliding board body can be prevented from cracking or being broken and the sliding board of the composite structure is long in service life, safe, reliable and the like.