Corrugated board assembly, corrugated board thereof and corrugated board assembly method

A corrugated board comprises a board body and an extension board. The board body defines a lower end and an upper end opposite to the lower end. The board body comprises an engagement part protrudingly formed on the top and adjacent to the upper end and a positioning part disposed between the engagement part and the upper end. The extension board comprises a covering part protruded from the lower end toward the direction distal from the bottom of the board body and a bending part extending from the covering part upward. The bending part defines an engagement slot at the bottom of the board body which is separated from the covering part and has an opening facing thereto. During the assembly, a corrugated board is engaged at the engagement slot of another corrugated board by the engagement part, and the covering part of another corrugated board is connected against the top of the board body of the corrugated board and below the engagement part, thereby facilitating the assembly process and reducing the time req