The invention relates to the technical field of furniture, in particular to a bunk bed which comprises an upper bed board, a lower bed board, a lower support frame, an upper support frame and a fence. The lower support frame is used for supporting the lower bed board, the upper bed board is supported above the lower bed board by the upper support frame, the fence is arranged on an outer side of the upper bed board, and the upper bed board is movably arranged relative to the lower bed board and can move in the horizontal direction and the vertical direction; the upper bed board can move to a position right above the lower bed board or can move to a side of the lower bed board, so that the upper bed board and the lower bed board can be positioned on the same horizontal plane; the fence is slidably connected onto the upper bed board and can move up and down relative to the upper bed board, and fixing structures for keeping the fence at the uppermost position or the lowermost position are arranged on the upper bed board. The bunk bed has the advantages that the bunk bed is simple in structure and convenient to use, can be turned into a double bed by means of simple deformation, is high in structural stability and is safe and stable, and the utilization rate of the bunk bed can be increased.