In Concrete flat slab opening was provided to provide services or to decrease self-weight of the slab. The flat slab with opening system is commonly used in different types of civil structures such as parking floor, Commercial building. In the Present study, total 15 slabs were casted to check the Adequacy of flat slabs with openings of different sizes and shapes. At the center of slab openings are provided with rectangular and circular shape. For rectangular opening 150x100mm and 200x150mm sizes were provided, and for circular opening 150mm and 110mm diameter the sizes of opening were provided. In this study Finite Element analysis of the flat slabs is proposed. A comparative study is carried out between experimental & analytical design of 750x500x150 mm slab panels. The ANSYS 16.0 finite element software which is used to analysis reinforced concrete (RC) slab models. The load has been applied at slab to calculate the maximum and minimum displacement, strain, stresses at each slab. The average deflections of size 150x100 mm rectangular opening were reduced by 25.52% as compared with size 200x150 mm rectangular opening. Similarly for a circular opening of 110mm diameter lesser by 11.39% as compared with 150mm diameter of opening.