The utility model discloses an indoor stair with hidden stand columns and cross beams, which comprises a profile steel plate, first screws, connecting pieces, a mounting plate, second screws, a panel and side plates, the two connecting pieces are fixedly connected to the outer walls of the two sides of the profile steel plate through the first screws, the connecting pieces are fixedly connected to the mounting plate through the second screws, and the panel is fixedly connected to the profile steel plate through the second screws. A panel is arranged on the upper surface of the profile steel plate, a side plate is arranged on the outer wall of one side of the profile steel plate, and the mounting plate and the side plate are arranged at the bottom end of the panel; the installation plates are installed through the second screws embedded in the wall body, the profile
steel plates are installed on the installation plates through the connecting pieces, the profile
steel plates serve as step plates, the function of the stairway is achieved, and therefore stairway columns and stairway beam structures are omitted, more
living space is released, indoor continuity is enhanced, and the service life of the stairway is prolonged. The decorative
steel plates are wrapped by the panels, attractiveness of the staircase is improved, and the panels are designed in a plug-in mode, so that the staircase has the advantages of being convenient to install and replace.