Abstract: A support and formwork free pre-installing staircase technique is proposed to improve the construction efficiency of current staircases, and this technique satisfies the architecture function and the construction safety. By the second design of traditional staircases, the related stair components were transformed into assembly-type staircase structures. The individual components of the staircase are prefabricated by the factory after the in-depth design, and then transported to the construction site for installation. In a same floor, before the construction of the vertical structure, the components of the staircase are installed first. After that, a complete and stable staircase structure is quickly formed, which can be directly used during the construction. The whole process of this technique avoids of using any support and formwork, so it means the passageway is always clear. Besides, the labor intensity is also reduced and the construction speed of the project could be accelerated.