Abstract: In order to study the mechanical properties of improved composite floor formed with the steel-bars truss and detachable formwork in the construction stage, an experimental study of mechanical performance of rapid assembled floor of two pieces of the same size and structure, one was hinged at both ends and the other was fixed at both ends, was conducted under the uniform load. The results show that the deflection of rapid assembled floor under the circumstance of both ends fixed. When the live load is 1.5 kN/m², the deflection can meet the design specification requirements of composite slab. The calculation methods of the construction stage and the application stage of steel-bar truss by force analysis were put forward, and were combined with a specific case for calculation and analysis. The calculation and test results are in good agreement. Lastly, the market value of the floor was demonstrated by an engineering case.