This paper evaluate the influence of floor slab on the performance of RC, SRC coupling beam in flat plate structure. It is validated through FEM model using Ansys program. The analysis results are evaluated based on displacement, stiffness, strain and effective slab width. The slab width at the beam-wall connection is based on ACI318-05, Eurocode2004 and KBC2009 provisions. The analysis results for the effect of floor slab suggest to be considered the effect of floor slab for coupling beam design in flat plate structure.