The principles of cast-in-place reinforced concrete hollow beamless building structure system, the design principle of side support hollow building cover, and the stiffness calculation were introduced. According to the provisions of CECS175[1], "when the elastic stiffness difference between the two directions of hollow floor slab in the straight cylinder and horizontal cylinder does not exceed 10%, the anisotropy of the floor slab can be ignored, and the same internal force analysis method as the ordinary solid building cover is taken", the implementation of the side support building cover design in PKPM software is analyzed and explored, and the design ideas and methods that can be calculated as equal thick solid slabs in the PKPM software are proposed, and relevant tables are drawn for the designer’s reference.