Composite board

The invention relates to a composite board which comprises a composite board body, a first through hole and a second through hole are formed in the composite board body, the first through hole communicates with the second through hole, the first through hole and the second through hole are perpendicular to each other, and a telescopic extension board is movably arranged in the first through hole; an existing composite board structure is improved, a combined structure of the first through hole, the second through hole and the telescopic extension board is additionally arranged on the improved composite board, and in the combined structure, the telescopic extension board can do telescopic motion in the telescopic extension board, so that after the telescopic extension board moves to the composite board body, the telescopic extension board can stretch out and draw back. The composite board body can be conveniently moved and mounted, and meanwhile, after the telescopic extension plate retracts into the first thro