A bottom bed combination includes a first bed bottom, a second bed bottom, two fastening units and a plurality of stands. The first bed bottom includes a first bed frame, a first bed board, a plurality of first bases a first linkage and a first electric cylinder. The second bed bottom includes a second bed frame, a second bed board, a plurality of second bases, a second linkage and a second electric cylinder. Each of the fastening units includes a mount mounted on the first bed frame and the second bed frame, and a pin extending through the mount, the first bed frame and the second bed frame. The stands are respectively secured on the first bases, the second bases and the fastening units.